Disclosed is a coherent combined capture subcode detection method based on delay multiplication. The method comprises the following steps of 1, capturing dual-channel combined main codes; 2, obtaining a relation sequence rs[k] of subcodes and navigation messages; 3, performing delay multiplication on the relation sequence of the subcodes and the navigation messages to obtain xdif[k]; 4, performing delay multiplication on a local sequence to obtain ydif[k], and calculating a correlative peak of the xdif[k] and the ydif[k]. Due to the steps, two-channel coherent combination capture of new system signal main codes and subcodes is achieved, the automatic bit synchronization effect is achieved, the problem that a single-channel capture method is low in energy utilization rate is solved, and the dual-channel capture subcode phase detection function is achieved.