NOVELTY - A biomass briquette solid fuel comprises (in parts weight) a biomass raw material (30-100), a secondary exothermic material (0-40), a combustion catalyst (0-40), a binder (0-40), and a plasticizer and other additives (0-30). The solid fuel is molded by high temperature-high pressure extrusion using a press machine. The biomass raw material is Miscanthus purpurascens, Phragmites communis, corn stems, rice hull, rice straw, grain residue, medical herb residue, sawdust, fallen leaves, and other vegetable cellulose.    USE - Biomass briquette solid fuel.    ADVANTAGE - The biomass briquette solid fuel uses economical waste plastic as binder, has high calorific value, and can be mass-produced.    DETAILED DESCRIPTION - A biomass briquette solid fuel comprises (in parts weight) a biomass raw material (30-100), a secondary exothermic material (0-40), a combustion catalyst (0-40), a binder (0-40), and a plasticizer and other additives (0-30). The solid fuel is molded by high temperature-high pressure extrusion using a press machine. The biomass raw material is Miscanthus purpurascens, Phragmites communis, corn stems, rice hull, rice straw, grain residue, medical herb residue, sawdust, fallen leaves, and other vegetable cellulose. The secondary exothermic material is coal dust. The binder is waste plastic e.g. polyethylene, polypropylene, polysulfone, polyethylene terephthalate, and/or nylon. The combustion catalyst is sodium silicate, fly ash, silica fumes, kaolin, zeolite, bentonite, and/or loess. The plasticizer and additive are bis(2-ethylhexyl)phthalate, diisononyl phthalate, bis(n-butyl)phthalate, butylbenzyl phthalate, diisodecyl phthalate, di-n-octyl phthalate, diisooctyl phthalate, diethyl phthalate, diisobutyl phthalate, di-n-hexyl phthalate, rosin, trimethyl trimellite, tri-(2-ethylhexyl)trimellite, tri-(n-octyl,n-decyl)trimellite, tri-(heptyl,nonyl)trimellite, n-octyl trimellite, bis(2-ethylhexyl)adipate, dimethyl adipate, monomethyl adipate, dioctyl adipate, dibutyl sebacate, dibutyl maleate, diisobutyl maleate, N-ethyl-p-toluenesulfonamide, N-(2-hydroxypropyl)benzene sulfonamide, N-(n-butyl)benzenesulfonamide, tricresyl phosphate, triethylene glycol dihexanoate, tetraethylene glycol diheptanoate, triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, trioctyl citrate, acetyl trioctyl citrate, trihexyl citrate, acetyl trihexyl citrate, butyryl n-trihexyl citrate, trimethyl citrate, camphor, sorbitan monostearate, naphthalene, paraffin, linseed oil, soybean oil, stearic acid, and/or sorbitol.