Abstract: The SiC piezoresistive pressure sensor is an important tool to realize the in-situ measurement of high temperature dynamic pressure on the aircraft surface. In order to improve the performance of the sensor and reduce the metal-semiconductor contact impedance, the fabrication and performance of n-type 4H–SiC ohmic contact are studied. Phosphorus (P) ion implantation is employed on the SiC substrate by the ion implantation process. Based on the Monte Carlo model, the process is simulated and designed by the SRIM software. And the n-type heavy doping is realized. The composite metal layers Ta/Ni/Pt were used as the metal electrode. An ultra-high temperature vacuum annealing process was studied to realize the 4H–SiC ohmic contact. The electrical characteristics of ohmic contact are tested by I–V method. And the specific contact resistance ρ_c is measured by the four probe method. The results show that fine ohmic contact can be achieved under the conditions that the concentration of the phosphorus (P) ion implantation is 3 × 10²⁰ cm⁻³, the annealing temperature is 1000 ℃ and the holding time is 20 min. The specific contact resistance ρ_c is 4.64 × 10⁻⁵ Ω·cm². The rate of change of ρ_c between 20 ℃and 600 ℃ is as low as 6%. It shows that the ohmic contact has very low contact impedance and good temperature stability. The thermal zero drift of the SiC piezoresistive pressure sensor caused by contact impedance is reduced.