Aiming at the variation characteristics of fault vibration waveform caused by the fracture fault of gas valve of reciprocating compressor,in order to improve the recognition rate of common late fracture type fault in valve plate,a diagnosis algorithm based on optimal variational modal decomposition (OVMD) and 3D singular spectrum fusion was proposed.Through VMD parameter optimization,multifractal detrended fluctuation analysis (MFDFA) was used to extract 3D singular spectrum parameters of modal components to analyze,eigenvalues of modal components under different working conditions were extracted through dimension reduction combined with kernel principal component analysis,and a complete diagnosis and recognition fusion scheme of OVMD_MFDFA was established.Simulation test and algorithm comparison show that this method can be used to effectively improve the efficiency and accuracy of fault diagnosis of annular gas valve plate crack.