The invention discloses a method for determining the firmness degree of a pine tree by detection equipment. The measuring equipment consists of a radar, a soil compaction determinator and a control instrument, and the radar and the soil compaction determinator are connected to the control instrument. According to the method, the control instrument sends an instruction of discriminating the stability of the pine tree to a detection device, the radar in the measuring equipment detects the pine tree root distribution width, the vertical root depth, the pine tree height and the diameter of the pine tree trunk, the soil compaction determinator measures the soil compaction degree, the radar and the soil compaction determinator transmit the measured data to the control instrument, the control instrument is internally provided with operation control program for discriminating the pine tree safety performance, receives data, performs data analysis and processing, and outputs the determination result to a display screen of the controller. By determining the stability of the pine tree, tipping of the pine tree can be effectively prevented, also personal safety and property of people can be protected without loss, and accidents can be avoided.