The invention provides a lower palaeozoic tilted stratum true thickness calculation method, comprising: a first step of performing fine layer interpretation on a plurality of standard reflection layers; a second step of: performing depth conversion on time layer data based on the standard reflection layers, and making a plane isobath map; a third step of calculating stratum thickness parameters; and a fourth step of calculating stratum true thickness. The lower palaeozoic tilted stratum true thickness calculation method is simple and easy to operate, and can improve the calculation accuracy of stratum true thickness, better understand lower palaeozoic stratum growth and predict each segment of reservoir stratums.