A method for analyzing influence factors of production decline of an oil and gas field includes the following steps that A, an influence factor set is determined; B, an analysis sequence is determined according to historical data; C, non-quantity processing is conducted on analysis sequence data; D, by the adoption of an improved grey correlation analysis method, influence factor association degrees are obtained and ranked; E, by the adoption of a combined hierarchical analysis method, factor weights are calculated and ranked; F, comprehensive analysis is conducted on the sequence obtained in the step D and the sequence obtained in the step E, a final influence degree sequence is obtained, and comprehensive analysis of the influence factors of production decline of the oil and gas field is achieved. According to the method, the determining mode of an identification coefficient p of a conventional grey correlation analysis method is improved, and subjectivity brought by empirical selection is eliminated; by means of the combined hierarchical analysis method, the importance degrees of the influence factors are determined from the subjective aspect and combined with an objective result. Calculation results obtained through the subjective method and the objective method are combined, so that an analysis result is more scientific, accurate and reasonable.