A resistance arranging system and method based on a RS-485 network are disclosed. A detection packet is generated and a circuit loop is received, so that the detection packet is taken as a basis signal and the received detection packet through the circuit loop is taken as a comparison signal, and push-up, pull-down and terminal resistors are arranged by controlling the switch according to the basis signal and the comparison signal, whereby achieving in a technical efficacy of convenience of promoting the resistors arrangement.