Truck carriage volume is measured with laser pulse time-of-flight range finding. By this scheme, the carriage part can be correctly segmented from the whole truck with 2~6 axles and calculated. With the third height moment, which is based on the gray moment for edge detection algorithm in digital image processing, the head and underframe of trucks with all kinds of axles are divided and computed for the volume of the carriage. Especially for 6-axle truck with the bench-shape, the point of bench turn and volume of the carriage are accurately calculated. Besides, using the technique of rolling-over and merging of the cross section data of truck body, the number of laser scanner is downsized to 2. The above techniques are already utilized in the project for carriage volume measurement. With a lot of results proved, carriage volume of trucks can be rightly calculated.