The invention discloses a method for detecting an internal environment of a nuclear equipment pipeline by a snake-like robot. The method comprises the following steps: (1) collecting an internal image of nuclear equipment by a detection system, detecting the nuclear radiation density, the pipeline temperature, the humidity, the pressure and a barrier in the nuclear equipment, and simultaneously monitoring the position of a snake body by a positioning system in real time; (2) transmitting data to a host computer by the detection system and the positioning system in real time; (3) generating a snake body motion gait instruction by the host computer, and transmitting the snake body motion gait instruction to a control system; (4) receiving the instruction and analyzing the corresponding motion program by the control system, controlling a corresponding joint driver to work according to the motion condition required by each joint module, driving the corresponding joint module to move and changing the real-time motion gait of the snake body; and (5) circulating the steps (1) to (4) until the snake-like robot finishes detection of the whole internal environment of the nuclear equipment. The method is reasonable in design, and convenient and fast to operate, and can be successfully applied to the field of pipeline detection of the nuclear equipment.