The utility model provides an engine knock protection device, its hydraulic pressure chamber or atmospheric pressure chamber that includes the piston department of fixed mounting in the cylinder, this hydraulic pressure chamber or atmospheric pressure chamber include the cavity part of two at least intercommunications, it passes through the break -make part and realizes along the axial arrangement of cylinder, the break -make between the cavity part. Simultaneously the utility model also provides an engine cylinder and the engine that have this engine knock protection device. The utility model provides a problem that risees of the instantaneous combustion pressure that results in because of early fire among the prior art, protected spare part and engine in the engine not to receive the damage, reduced the emergence probability of early fire of follow -up endless and knockings simultaneously.