As path loss prediction for a near-ground wireless channel is an essential issue in most research activities of wireless sensor networks, this paper measures and analyzes the transmission characteristics of a 2.4 GHz wireless signal in a grassland environment and performs a linear regression for collected data based on the least square method. The results indicate that the log-distance based model is still suitable for the path loss modeling in the near-ground wireless channel, and the fitting accuracy of the two-slope model is better than that of the one-slope model. Furthermore, the breakpoint position is determined by the antenna height, and the path loss indexes are less than 2 or between 3 and 4 before or after the breakpoint. With comparison of the predicted path loss and the measured path loss in a far-field, it proves that the prediction accuracy of the two-slope model is superior to that of the one-slope model. Finally, the performance of the generic models and the proposed two-slope model is compared, which suggests that the generic models are not suitable for research activities in the near-ground environment and the proposed model has a more practical value for research on wireless sensor networks.