NOVELTY - A tetrahydrothiophene onium type ion liquid contains a tetrahydrothiophene onium salt (1, 2, 3 or 4).    USE - Tetrahydrothiophene onium type ion liquid is used for non-aqueous electrolyte and phase shifting catalyst, (both claimed) solvent of enzyme catalysis reaction and electrolyte for dye sensitized solar cell.    ADVANTAGE - The tetrahydrothiophene onium type ion liquid is manufactured efficiently.    DETAILED DESCRIPTION - A tetrahydrothiophene onium type ion liquid contains a tetrahydrothiophene onium salt of formula (1, 2, 3 or 4).    R=1-20C alkyl, 1-20C alkenyl having one or more double bonds, 1-20C alkynyl having one or more triple bonds, or optionally saturated 3-7C naphthenic base optionally substituted by 1-6C alkyl, fluorine, chlorine, bromine, iodine, cyanogen group, sulfur cyanogen group, selenium cyanogen group or nitryl, or not directly adjacent with one or more carbon atoms with sulfur atom substituted by -O-, -C(O)-, -S-, -S(O)-, -SO2-, -SO3-, -N=, -N=N-, -NH-, -NR'-, -P(O)R'-, -O-P(O)R' or -N(R')=N-;    R0=H, 1-20C alkyl, 1-20C alkenyl having one or more double bonds, 1-20C alkynyl having one or more triple bonds, or optionally saturated 3-7C naphthenic base optionally substituted by 1-6C alkyl, fluorine, chlorine, bromine, iodine, cyanogen group, sulfur cyanogen group, selenium cyanogen group or nitryl, or not directly adjacent with one or more carbon atoms with sulfur atom substituted by -O-, -C(O)-, -S-, -S(O)-, -SO2-, -SO3-, -N=, -N=N-, -NH-, -NR'-, -P(O)R'-, -O-P(O)R' or -N(R')=N-;    R'=optionally fluorinated 1-6C alkyl, optionally saturated 3-7C naphthene base, (un)substituted phenyl or (un)substituted heterocycle, alkyl of R' is partially substituted by difluorine methyl, trifluorine methyl, trifluorine ethyl, pentafluorine ethyl or heptafluorine propyl;    A-=I-, Br-, (Cl)-, (N(CN)2)-, (N(SO2CF3)2)-, (PF6)-, (BF4)-, (NO3)-, (C(CN)3)-, (B(CN4))-, (CF3COO)-, (ClO4)-, (R1SO3)-, (RfSO3)-, ((RfSO2)2N)-, ((RfSO2)3C)-, ((FSO2)3C)-, (R1CH2OSO3)-, (R1C(O)O)-, (Rf'C(O)O)-, (CCl3C(O)O)-, ((CN)2CR1)-, ((R1O(O)C)2CR1)-, (P(CnF2n+1-mHm)yF6-y)-, (P(C6H5) yF6-y)-, (R12P(O)O)-, (R1P(O)O2)2-, ((R1O)2P(O)O)-, ((R1O)P(O)O2)2-, ((R1O)(R1)P(O)O)-, (Rf2P(O)O)-, (RfP(O)O2)-, (BFzRf4-z)-, (BFz(CN)4-z )-, (B(C6F5)4)-, (B(OR1)4)-, (N(CF3)2)-, (AlCl4)- or (SiF6)2-;    Rf',Rf=fluorinated 1-20C alkyl, fluorinated 2-20C alkene having one or more double bonds, fluorinated phenyl or optionally saturated 3-7C naphthene base, substituted by fluorinated alkyl, linked to a pair through single bond or double bond and one or more carbon atoms which are not position of hetero atom in Rf or Rf' is substituted by -O-, -C(O)-, -S-, -S(O)-, -SO2-, -N=, -N=N-, -NR'-, -PR'-, -P(O)R'-, R'-O-SO2- or R'-O-C(O)-, f' excludes tri-fluorine methyl;    R1=1-20C alkyl, 2-20C alkene having one or more double bonds, 2-20C alkynyl having one or more triple bonds, optionally saturated 3-7C naphthene base, substituted 1-20C alkyl, optionally substituted by fluorine, chlorine, bromine, iodine, cyano, sulfur cyano, selenium cyanogen or nitryl, or one or more carbon atoms which are not at a position of hetero atom in R1 is substituted by -O-, -C(O)-, -C(O)O-, -S-, -S(O)-, -SO3-, -N=, -N=N-, -NR'-, -PR'-, -P(O)R'-, -P(O)R'O-, OP(O)R'O-, PR'2=N-, -C(O)NH-, -C(O)NR'-, -SO2NH- or -SO2NR'-;    n=1-20;    m=0, 1, 2 or 3;and    y=0, 1, 2, 3 or 4.    R0 is mutually contained in alpha location of R. R0 is mutually connected through single bond or double bond. R1 is linked through single bond or double bond. An INDEPENDENT CLAIM is included for method for preparing tetrahydrothiophene onium type ion liquid which involves dripping and stirring iodoalkane in tetrahydrothiophene in mol ratio of 1.05-1.5, pumping vacuum from the reactor, filling with nitrogen gas, stirring, refluxing and reacting the mixture at 50-70 degrees C for 12-48 hours, scrubbing by de-ionized water, extracting by methylene dichloride, steaming and drying at 60 degrees C for 2 hours the resulting mixture to obtain tetrahydrothiophene onium type ion liquid with iodine ion as anion.