The present invention discloses a submarine seismic monitoring apparatus and system based on the submarine Internet of things. A sea surface buoy network device and a submarine network device in the monitoring apparatus are connected by using an anchor system; the submarine network device and a submarine seismic detection device are connected by using a submarine photoelectric composite cable; there are one or more submarine seismic detection devices; the sea surface buoy network device includes a satellite transceiver apparatus, an Internet of things platform server, a network time server, and an autonomous energy supply apparatus; the submarine network device includes a photoelectric separation cabin, a submarine server, a bottom anchor weight block, and a mechanical releaser; and the submarine seismic detection device includes multiple submarine seismometer network nodes, where the multiple submarine seismometer network nodes are successively connected in series end to end by using the submarine photoelectric composite cable. The apparatus and system in the present invention not only can be used for submarine structure detection, but also can be used for earthquake disaster and tsunami warning, and can implement autonomous energy supply, long timing, and unattended operation.