The invention relates to a multi-exit gather stream analyzing method for a network on chip delay bound. The multi-exit gather stream analyzing method is realized through the following steps: step a, confirming a target stream, to be more specific, selecting one stream to serve as the target stream, and enabling the other streams to serve as conflict streams; step b, searching the conflict streams and cutting into standard streams, finding all the conflict streams in a target stream route and cutting into I-type standard streams and II-type standard streams; step c, calculating a standard stream arrival curve so as to obtain the arrival curve of each type of standard streams; step d, calculating the bottleneck node of each sub-stream of each II-type standard stream; step e, calculating the target stream delay bound according to a formula. The multi-exit gather stream analyzing method for the network on chip delay bound is more precise to calculate the target stream delay at the analysis level, the analysis result is closer to the maximum delay obtained in performing practical simulation, and accordingly the network performance analysis is greatly facilitated.