Three-dimensional (3D) printing device and printing method thereof

The invention discloses a three-dimensional (3D) printing device and a printing method thereof. The 3D printing device comprises a base, an exposure mechanism, a control mechanism and a printing mechanism, wherein the exposure mechanism and the control mechanism are arranged in the base; the printing mechanism is arranged on the base; the printing mechanism comprises a mould, a printing platform arranged on the mould in a sliding way, and an inclined pulling assembly arranged at the bottom end of the mould; the inclined pulling assembly comprises a mounting bracket fixedly arranged at the upper end of the base, and a support frame movably connected with the mounting bracket by a connecting piece; the support frame is provided with a resin frame; the support frame is further provided with a pull rod at the bottom of the side opposite to the connecting piece; the pull rod is connected with a drive motor; the exposure mechanism comprises a projector; a projection lens of the projector is arranged under the resin frame; the exposure from bottom to top is adopted, so that the middle of a curing layer is not convex due to surface tension, and the flatness is guaranteed; the inclined pulling assembly is adopted, so that the service life of a film on a transparent bottom plate of the resin frame is greatly improved.