The invention discloses a bus polling method and device. The bus polling method comprises the steps that polled equipment is divided into an offline equipment group and an online equipment group; in the current diagnosis period, a first polling request is sent to each polled device of the offline device group for n times, n is greater than or equal to 1, and a second polling request is sequentially sent to each polled device of the online device group for multiple times; when a first polling response of polled equipment of the offline equipment group is received and it is judged that the polled equipment is online according to the received first polling response, the polled equipment is moved into the online equipment group; and when the second polling response of the polled device of the online device group is not received and it is judged that the polled device is offline according to the fact that the second polling response is not received, the polled device is moved into the offline device group. According to the invention, different polling times are set for the offline device and the online device, so that the polling period is not increased because the device on the bus is offline.