The invention discloses a pipeline monitoring system for natural gas hydrate exploitation. The pipeline monitoring system comprises a subsea test tree, seven temperature pressure sensors and one or more temperature-measuring cables which are arranged in a wellbore. The pipeline monitoring system has the beneficial effects that the low-cost sensors are arranged in the designated location in the wellbore in a targeted mode, then the one or more temperature-measuring cables are arranged along the depth of the whole wellbore, and then the temperature and pressure parameters of all the sensors andthe continuous temperature of the whole wellbore are reported to an upper computer; through existing analysis and calculation, the sand and water output quantity and a secondary hydrate at a down-holeexploitation layer can be accurately understood to generate early warning and judgment, and an operator can inject a chemical inhibitor into a well in real time according to the calculation results;and by adjusting a working system, sand outlet is prevented, the water outlet quantity is accurately adjusted, and it is guaranteed that in the whole production process, the production negative pressure is controlled within the predetermined range.