Based on the methods and results of previous researches on detecting forest fires and urban fire smoke by S-band Doppler weather radar as well as the classification and comparison of 34 forest fire cases from 10 C-band radars in Yunnan Province, some unique indices of forest fire echoes by C-band mountain-top radars were obtained in this paper. The paper also put forward setting forest identification threshold according to radar altitude. Some new indices and methods, such as velocity field features, precipitation echo filtering, are introduced to detect forest fires. Then conducting radar detection to forest fires in such kinds of areas and operational practices proved to have achieved certain results by practical tests and field surveys. The main technical indices are as follows. Due to the effect of altitude difference of mountain radars, correspondly indices and parameters of different radars should be set respectively. According to the rising and drifting characteristics of forest fire echoes, the radar echo velocity is different from the surrounding echoes sometimes. By filtering clear air echo, clutter, ground object ehco, secondary echo, precipitation echo and identifying special echoes of velocity field, the suspected echoes of fire smoke can be obtained. These indices and methods could be used as reference for radar detection in the western mountains.