Abstract: Tianwen-1 is the first chinese probe to realize interplanetary flight between Earth and Mars. During the 6.5-month interplanetary transfer flight, it experienced four midway corrections and one deep space maneuver control. In this paper, the dynamic model during deep space exploration is analyzed, and the principle of celestial center conversion during transfer flight is formulated. It is necessary to replace the celestial center with the sun after leaving the earth's influence sphere; The use of planetary ephemeris is analyzed, and it is determined that the use of de436 ephemeris has the least impact on orbit determination; an accuracy evaluation method based on daily iterative orbit determination strategy is developed. Based on the analysis of measured data, it is shown that the orbit determination position error in interplanetary transfer section is better than 2km, and the velocity error is better than 20mm / s (1 σ).