The invention discloses a method and a device for controlling 
gas supply of dual-fuel engine, which can effectively solve the problems of starting difficulty in northeast region, and applies closed-
loop control to achieve a reasonable air-fuel ratio between air and fuel; when the temperature of 
coolant is increased, the supply of 
natural gas is 
cut off and liquefied gas is supplied for 
combustion, thus under the premise of ensuring the dynamic performance of the engine, gas is reasonably used; meanwhile, an electronic gas-saving gate device is used, which can overcome the drawbacks of engine 
accelerograph and guarantee securer and more efficient operation. The method for controlling 
gas supply of dual-fuel engine comprises the following steps: a softness controlling method for quickly 
cutting off 
natural gas and liquefied gas, a closed-loop controlling method for excess air ratio of the 
natural gas and the liquefied gas, an automatic repairing function for failure, and a bad condition self-learning controlling method. The device for controlling 
gas supply of dual-fuel engine comprises a supply 
system for natural gas and liquefied gas, a closed-loop 
actuator, a supply controlling module and a micro controller, a CAN communication module and a serial-port communication module.