A method for detecting and scribing the capacity of a liquid cargo tank of an LNG transport ship comprises the following steps: carrying out three-
dimensional precision measurement on a block in advance by using a
laser total station, carrying out
data analysis on the block by using a simulated loading (Eco-OTS) technology, and drawing a detection
position line at a detection position according to
analysis data; wherein one simple tool is matched with a
laser range finder to detect the distance of a straight structure in the cabin, and the other simple tool is matched with a
total station to detect CM points in the cabin; in real ship body cabin capacity detection, according to each detection
position line which is drawn in advance, a simple tool is placed at the
position line, and a
laser range finder is matched for detection; and the other tool is placed at the CM point, and the
total station detects the mark point of the tool to obtain detection data. According to the method,
data detection is more visual and reliable, correction caused by data errors due to unstable use of the range finder in the detection process is prevented, the precision and efficiency are improved, and a large amount of construction cost and time are saved.