The invention provides a trench silicon carbide power device with low on-resistance and a manufacturing process thereof. The cell of the trench silicon carbide power device comprises an N-type substrate, an N-type epitaxial layer and a trench, wherein the trench is internally provided with a gate oxide layer and a polysilicon gate, a P-type body region, an N-type source region and a P+ body contact region are arranged on the two sides of the trench, a P shielding layer is arranged below the trench, and an N-type buried layer is arranged on the side of the P shielding layer. The manufacturing process of the N-type buried layer comprises the steps of epitaxially growing a first part of an N-type drift region on the N-type substrate, forming a P shielding layer and an N-type buried layer on the first part of the N-type drift region by adopting an ion implantation process, continuing to epitaxially form a second part of the N-type drift region, and carrying out a subsequent process flow. According to the invention, two sides of the P shielding layer are provided with the N-type buried layers, the electric field peak is moved downwards, the trench corner electric field is reduced, the interface state density and defects are reduced, and the reliability of the gate oxide layer is improved; and an N-type buried layer below is eliminated, the gate charge of the device is reduced, the switching characteristic is improved, and the withstand voltage of the device is further improved.