In order to solve the problem of insufficient ability of small target detection in the original single shot multibox detector (SSD) target detection algorithm, an improved SSD target detection algorithm is proposed. VGG19 is used as the feature extraction network, Conv3_3 convolution feature graph is introduced into the low-level feature map, the transpose convolution operation is carried out on Conv4_4, and the Conv4_3 obtained by transpose convolution is spliced with the feature map of Conv3_3. In the test, the VOC data set is used to train and test the model. The results show that the algorithm can improve the detection ability, the target detection accuracy can be improved by 3.6% compared with the original SSD algorithm, and the effect of small target detection is also significantly improved.