The invention discloses a stepping motor subdivision driving device with current vector constant amplitude control, which comprises an RS232 interface circuit, an optocoupler isolation circuit, an LED indication circuit, a voltage and current protection circuit, a subdivision driving power supply circuit, a main control unit, a power The drive circuit, two-phase stepper motor and current detection and conditioning circuit, the RS232 interface circuit, optocoupler isolation circuit, LED indicator circuit, voltage and current protection circuit, subdivision drive power supply circuit and current detection and conditioning circuit are respectively connected with the main control unit connection; the main control unit, the power drive circuit are connected to the two-phase stepping motor in sequence, and the power drive circuit is connected to the current detection and conditioning circuit in sequence. The current vector constant-amplitude control stepping motor subdivision drive device of the present invention can overcome the defects of poor adjustability, low control precision, low reliability and poor repeatability in the prior art, so as to achieve good adjustability and control The advantages of high precision, high reliability and good repeatability.