The invention relates to a channel-type dangerous liquid detection device and a channel-type dangerous liquid detection method. The channel-type dangerous liquid detection device comprises a perspective scanning detection device, a linear tomography detection device, and a processing and control unit. The perspective scanning detection device gets a perspective view of liquid in a container on a conveyor belt. The linear tomography detection device gets the tomography data of the liquid in the container. The processing and control unit rearranges and compensates the linear tomography data to get the projection data of the liquid in the container, reconstructs a cross-sectional image of the liquid at a position using a double-energy reconstruction algorithm, calculates the high-energy and low-energy attenuation coefficients, the effective atomic number and the electron density, and compares the four indicators with corresponding thresholds to judge whether the liquid in the container is dangerous. The detection device can carry out detection continuously, and is of low cost. Whether a liquid is dangerous is judged by compensating missing projection data and according to the four indicators. The identification precision of dangerous liquid is improved.