The invention discloses a piston connection rod assembly of an engine and the engine with he same. The piston connection rod assembly comprises a piston, a piston pin, a connection rod, a sliding block, a spring and a pressure-relief valve, wherein containing space is limited in the piston, and an oil cavity is formed in the containing space; the piston pin can be contained in the containing space in a vertical moving mode, and an oil channel is formed in the piston pin; the connection rod is sleeved on the piston pin and provided with an oil inlet port communicated with the oil channel; the sliding block is sleeved on the piston pin and positioned in the containing space, and a sliding block oil channel communicated with the oil channel and the oil cavity is arranged in the sliding block; the spring abuts against the position between the inner wall of the containing space and the side of the lateral wall opposite to the sliding block oil channel of the sliding block; the pressure-relief valve is arranged on at least one of the piston pin and the piston. By means of the piston connection rod assembly, the position of the piston relative to the connection rod can be changed, the volume of a combustion chamber of the engine is changed, and the purpose of regulating the compression ratio is achieved.