The present invention discloses a ship still water shearing force and bending moment calculating method which comprises the following steps of: establishing three-dimensional photoetching format models of a ship housing and all compartments, i.e. STL models; calculating a floating state of a ship in a random loading state; and calculating a buoyancy distribution curve, a weight distribution curve, a load distribution curve, a shearing force distribution curve and a bending moment distribution curve of the ship. According to the present invention, the floating state of the ship under the random loading condition is calculated on the basis of the STL models; transverse inclination and longitudinal inclination of the ship can be simultaneously calculated; the defect of only calculating a longitudinal inclination angle of the ship in a conventional method is overcome; and calculation accuracy is improved. According to the present invention, on the basis of the ship housing STL model, the buoyancy curves of the ship under the random transverse inclination and longitudinal inclination can be calculated. According to the present invention, the concept of a weight distribution table of the compartments is disclosed and in the calculating process, volume distribution among frames only needs to be interpolated according to a loading height, and not only calculation accuracy can be improved, but also calculation efficiency can be ensured.