NOVELTY - Device for controlling concentration of methanol solution for direct methanol fuel battery comprises upper cylinder and lower cylinder, both are in parallel with each other axially and cylinder wall are embedded with each other up and down, and several thin bores are opened at embedded portion, and polyfluorotetraethylene (16) is filled in thin bores, and external cylinder wall (15) of upper cylinder inputs pure methanol (3) from guide tube (14), and one end of lower cylinder connects with one external liquid pump (7); and driving mechanism comprising gear (20).    USE - Device for controlling concentration of methanol solution for direct methanol fuel battery (claimed).    ADVANTAGE - The device for controlling concentration of methanol solution for direct methanol fuel battery can control the methanol concentration according to the loads of the galvanic pile and it is simply structured and convenient to maintain.    DETAILED DESCRIPTION - Device for controlling concentration of methanol solution for direct methanol fuel battery comprises upper cylinder and lower cylinder, the two are in parallel with each other axially and cylinder wall are embedded with each other up and down, and several thin bores are opened at embedded portion, and polyfluorotetraethylene (16) is filled in thin bores, and external cylinder wall (15) of upper cylinder inputs pure methanol (3) from guide tube (14), and one end of the lower cylinder connects with one external liquid pump (7); driving mechanism comprising gear (20), upper portion of one end comprises the driving rod (22) with rack, electric motor (21) and piston (17), where the gear (20) engages with the driving rod (22), and the piston (17) connects with the other end of driving rod (22), and the electric motor (21) drives the gear (20) to lead the piston (17) to move back and forth along the cylinder wall in horizontal direction inside the external cylinder by driving rod (22), and the change of direction or description of the electric motor (21) interrelates with the compared result between the methanol concentration detected by the methanol sensor (9) locating on the methanol flowing direction and the inputting methanol concentration expected by galvanic pile; fixing sleeve (19) which is fixed on the external cylinder wall (24) of the lower cylinder by the fixing rod (18) and driving rod (22) passes through the fixing sleeve (19) axially.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a device for controlling concentration of methanol solution for direct methanol fuel battery.    Liquid pump (7)    Methanol sensor (9)    External cylinder wall (15)    Piston (17)    Gear (20)