With the rapid development of the economy, the influence of digital marketing on consumer buying behavior is becoming more and more important. This paper first introduces the consumer purchase behavior regression model (SICAS) for digital marketing. Secondly, a locally weighted linear regression model based on SGD is constructed using nonparametric linear regression, local weighting, and stochastic gradient descent algorithms. This model is used to regression analyze the factors affecting consumer purchase behavior and identify the important factors that affect consumer purchase decisions. Finally, the insights of a digital marketing approach to enhance consumer buying behavior are given. People who buy goods offline account for 30.7%, while the remaining 69.3% choose online shopping. With the development of the digital market economy, online purchases will become mainstream. The reliability coefficient is in the range of 0.851-0.949, the KMO is 0.924, the Bartlett value is 759.766, and the significance is P < 0.05. The variables’ high reliability and correlation make them suitable for factor analysis. The coefficients between the factors and consumer purchase decisions were 0.774, 0.805, 0.832, 0.332, and 0.894 (P < 0.01). The model R2 was 0.868 and F = 225.968 (p<0.05), indicating that the model is valid. Except for gender, there is a significant positive correlation (p<0.05) between all variables and consumer purchase decisions. Obviously, selecting appropriate digital marketing strategies is crucial to understanding consumer purchasing behavior.