The invention discloses a cross-network element end-to-end media plane detection device, which comprises a front-end media plane detection module, a rear-end media plane detection module and a call processing module, wherein the front-end media plane detection module is used for storing one or more sections of standard test tones, and when receiving a media stream test starting message, transmitting the stored standard test tones to the rear-end media plane detection module; the rear-end media plane detection module is used for receiving the standard test tones from the front-end media plane detection module, comparing the received standard test tones with own stored standard test tones and judging a media plane problem; and the call processing module is used for issuing an analogue call flow, and transmitting a media stream test starting command to the front-end media plane detection module. The invention also discloses a cross-network element end-to-end media plane detection method. By the device and the method, the media plane problem in a system can be timely discovered, the media plane problem detection efficiency can be improved, a failure detection cycle can be shortened and the normal running of the communication system can be ensured.