The present invention provides a method of searching for oil-gas reservoir based on TRAP-3D software, including: establishing a three-dimensional lithology and fault data cube of an exploration working area according to three-dimensional seismic data and logging data; dividing the three-dimensional lithology and fault data cube into several depth slices of the same depth, and performing an individual sand body unit division for each depth slice; sequentially inputting the depth slices of the three-dimensional lithology and fault data cube into the TRAP-3D software for oil-gas reservoir evaluation. The present invention imporves the accuracy of three-dimensional trap evaluation, is conducive to precise searching of the oil-gas reservoir, can plot a Sweet-Spot diagram on a plane, and get exhibits oil-gas trap amounts of different depths in a longitudinal direction, and can obtain a total trap amount of the oil gas reservoir in the exploration working area.