In view of the complex electromagnetic environment of modern electronic warfare， it is difficult to extract the effective features of composite jamming signals and identify them. In this paper， a combined jamming recognition algorithm based on smoothed pseudo Wigner-Ville distribution （SPWVD） and improved AlexNet is proposed. The algorithm uses the SPWVD to analyze the time and frequency of the composite jamming signal. Then the image processing technology is used to reduce the dimension of time-frequency characteristics. Finally， combined with the improved AlexNet model， the algorithm uses several small convolution kernels to replace the large convolution kernel， removes the full-connection layer 7 and the local response normalization module to reduce the network parameters and speed up the calculation， so as to realize the recognition of composite jamming signals. Simulation results show that when the jamming（signal） to noise ratio is 0 dB， the recognition rates of the target signal and six kinds of composite jamming signals are all above 90%. Compared with the AlexNet model， the improved network has significant improvement in recognition accuracy.