Improving farmers’ fertilization behavior through technical training is conducive to reducing agricultural non-point source pollution and maintaining soil health. The existing studies mainly discuss the impact of technical training on the adoption of soil testing formula fertilization (STFF) from the perspective of judging the training effect, but there are few further answers to how to improve the effect of technical training. Based on the theory of planned behavior and training transfer, this study adopted a logit model and OLS model to explore the role of training in the adoption of STFF, as well as the moderation effect of personalized information support. An empirical test was carried out using the survey data of farmers in Zhejiang Province, China. The results showed that participating in technical training is beneficial for farmers in adopting STFF, and receiving personalized information support can strengthen the promotion effect of technical training on the adoption of STFF. Further analysis reveals that there are certain differences in the above relationships among farmers with different operating scales. The findings could facilitate a deeper understanding of the improvement of technical training performance and accumulation of rural human capital and could also provide a useful reference for the policy formulation to optimize farmers’ fertilization behavior and promote sustainable agricultural development.