This paper investigates the effect of the interval remelting process on the forming quality of three-dimensional printing Ti-6Al-4V (TC4) samples. To improve the internal defects and hence the efficiency of forming samples with thick layers (150 μm), the optimized process mode of "surface remelting + internal interval remelting" was applied. Comparison tests with samples formed without remelting showed that interval remelting and layer-by-layer remelting significantly improved the surface quality of the samples, with little difference between the results of both processes. The tensile strength, yield strength, and elongation of the samples remelted with a one layer interval were 97.84 MPa, 45.96 MPa, and 0.9% higher, respectively, than those of the samples formed without remelting. The fracture morphologies showed river-cleavage and dimple fractures, with slightly more holes in the one-interval remelted sample than in the layer-by-layer remelted sample. The mechanical property improvements of both samples were very similar. Meanwhile, the microstructure of the sample was related to the laser interval remelting process. The one-interval remelted sample gave a uniform and dense surface and the highest microhardness (442.1 HV_0.3) among the samples.