The embodiment of the invention provides a combustor and a gas water heater with the same. The combustor comprises a plurality of fire grate single bodies arranged in parallel. A pre-mixing cavity isdefined by each fire grate single body. Each fire grate single body is provided with a gas inlet and fire holes, wherein the gas inlet and the fire holes are communicated with the corresponding pre-mixing cavity. The adjacent fire grate single bodies are arranged at intervals, and thus gas delivery channels are defined, wherein the distance between the central lines of any two adjacent fire gratesingle bodies is L, and L is larger than or equal to 10 mm and smaller than or equal to 30 mm. According to the combustor, by designing the distance between the central lines of any two adjacent firegrate single bodies to be larger than or equal to 10 mm and smaller than or equal to 30 mm, it is ensured that the combustor has good hot loads, and the combustor is low in working noise and stable inflame.