Abstract: The problem of orbit calculation dynamics in the upcoming asteroid exploration missions of China is studied.The demand of asteroid probe orbit calculation is analyzed，and the space-time reference system involved in asteroid orbit calculation is described，then the dynamical models to be considered in orbit calculation are discussed.The calculation formulas of various types of perturbation acceleration are given.The largest force model is the gravitational acceleration of the Sun，with magnitude about 10^-6km/s²，and the smallest is the asteroid body perturbation acceleration which is about 10^-12-10^-13km/s².The difference between ephemeris of Rosetta provided by ESA and that integrated from the dynamical model in this paper shows that the four-day arc segment position error is about 15m，velocity error is about 0.44mm/s，so the accuracy of the dynamical model is reliable.The above study can provide a reference for the orbit calculation of China′s asteroid exploration missions.

Key words: asteroid exploration, space-time reference system, orbit calculations, dynamical models, gravitational field, orbit perturbation