The invention relates to a drive control method and system for a large-caliber telescope arc motor. A DSP (Digital Signal Processor) event manager outputs six paths of drive signals; the six paths of drive signals are output to an intelligent power module after being subjected to optocoupling isolation; the intelligent power module outputs three paths of UVW voltage signals which are approximate to a circular magnetic field and the three paths of UVW voltage signals are added to an arc motor; a current mutual inductor measures each path of current; the current is input into a DSP buffer serial port for processing after subjected to A/D (Analog-to-Digital) conversion; a CPLD (Complex Programmable Logic Device) is used for processing an increment position signal generated by a coder and finishing interfaces of keyboard display, and the like; a rough and fine combined rotating transformer outputs an absolute position signal of the arc motor after passing through a digital converter; the signal is combined with the increment position signal processed by the CPLD to confirm the precise mechanical position of the arc motor; and motor phase conversion is realized after DSP processing. The invention can meet the requirement on a large radio telescope for a super-low speed arc motor and realize long time, super low speed, wide speed regulation and high precision tracking of a large-caliber millimeter wave/submillimeter telescope to a celestial body and has no creeping phenomenon at low speed.