A three-dimensional printing device (100, 200), comprising: a printing platform (130, 230), comprising a carrying surface (S1, S1'); a printing head (120, 220), disposed above the printing platform (130, 230); a sensor (121, 221), disposed above the printing platform (130, 230); and a controller (110, 210), coupled to the printing head (120, 220) and the sensor (121, 221), wherein the controller (110, 210) is configured to: analyze a first layer slicing data of a three-dimensional object to obtain a printing range, and operate the sensor (121, 221) to sense a plurality of sensing points (D1, D2, D3, D4) corresponding to the printing range on the carrying surface (S1, S1') of the printing platform (130, 230), so as to obtain a plurality of sensing parameters corresponding to the sensing points (D1, D2, D3, D4), determine whether the printing platform (130, 230) is inclined according to the sensing parameters, if the printing platform 15 (130, 230) is inclined, determine an object shape of a compensation object according to the printing range and the sensing parameters, and operate the printing head (120, 220) to pre-print the compensation object on the carrying surface (S1, S1') of the printing platform (130, 230) before printing the three-dimensional object. a printing platform (130, 230), comprising a carrying surface (S1, S1'); a printing head (120, 220), disposed above the printing platform (130, 230); a sensor (121, 221), disposed above the printing platform (130, 230); and a controller (110, 210), coupled to the printing head (120, 220) and the sensor (121, 221), wherein the controller (110, 210) is configured to: analyze a first layer slicing data of a three-dimensional object to obtain a printing range, and operate the sensor (121, 221) to sense a plurality of sensing points (D1, D2, D3, D4) corresponding to the printing range on the carrying surface (S1, S1') of the printing platform (130, 230), so as to obtain a plurality of sensing parameters corresponding to the sensing points (D1, D2, D3, D4), determine whether the printing platform (130, 230) is inclined according to the sensing parameters, if the printing platform 15 (130, 230) is inclined, determine an object shape of a compensation object according to the printing range and the sensing parameters, and operate the printing head (120, 220) to pre-print the compensation object on the carrying surface (S1, S1') of the printing platform (130, 230) before printing the three-dimensional object. analyze a first layer slicing data of a three-dimensional object to obtain a printing range, and operate the sensor (121, 221) to sense a plurality of sensing points (D1, D2, D3, D4) corresponding to the printing range on the carrying surface (S1, S1') of the printing platform (130, 230), so as to obtain a plurality of sensing parameters corresponding to the sensing points (D1, D2, D3, D4), determine whether the printing platform (130, 230) is inclined according to the sensing parameters, if the printing platform 15 (130, 230) is inclined, determine an object shape of a compensation object according to the printing range and the sensing parameters, and operate the printing head (120, 220) to pre-print the compensation object on the carrying surface (S1, S1') of the printing platform (130, 230) before printing the three-dimensional object.