Based on the data of regional economic growth in Guangdong Province from 2000 to 2019, this paper analyzes the impact of investment, consumption, human resources and export on regional economic growth based on semiparametric model. The conclusions can be gain as following: (1) Consumption and human resources have a greater role in promoting regional economic growth; (2) Investment has a nonlinear effect on regional economic growth. When the level of investment exceeds the threshold, it will no longer promote regional economic growth; (3) In the study of regional economic growth, the semi-parametric model has better fitting effect than the linear model, and is more suitable for the study of regional economic growth. The main suggestions are as follows: (1) We should increase the level of domestic demand and appropriately control the scale of investment. (2) Strengthen the training of human resources, improve the role of promoting regional economic growth