The cogasification experiments were carried out by an electric fixed-bed gasifier to explore the cooperative gasification mechanisms of straw and kitchen waste. The effects of temperature, equivalence ratio as well as mixing ratio of straw and kitchen waste containing rice and trench oil on the gasification behaviors were investigated, combining the characterizations with SEM and FTIR. The results showed that the CH4 release volume fraction of single trench oil could up to 90%, as for the mixtures of straw, rice, and trench oil, the rapid reaction of oil could increase the gasification temperature, promote the bond fractures of C(sic)C and C-H. Thereby those fractured matters could combine CO and H-2 to generate CH4, which consequently improved the gas quality from straw gasification. As the equivalence ratio being 0.1 at 800 degrees C, the actual calorific value of released gaseous from the mixture of straw, rice, and oil was at least 26% higher than the theoretical weighting value. When the mass ratio of straw, oil, and rice was 2:0.5:0.5, that superiority even reached 49.31%. Furthermore, in another fixed-bed gasifier without external heating, the mixture of sun-dried straw and actual kitchen waste containing much water could still achieve continuous gasification, and the experimental phenomena were similar to those above with the electric fixed-bed gasifier. The real calorific value of the mixture of straw and kitchen waste was still higher than the theoretical weighting value.