The invention relates to a method for measuring particle distribution in a fluidized bed heat exchanger by weighing, which mainly solves the technical problem of measuring the particle distribution inthe fluidized bed heat exchanger. The technical scheme of the invention is that the method comprises the following steps: (a) adding particles from a feeding port 17, starting a pump 14, and pushingthe particles to enter a tube array 2 through a lower tube box 10, enter a collecting tank 6 and then return to a particle tank 9 under the push of a liquid phase; (b) when particles appear in the collecting tank 6, recording a time t equal to 0, and when t is equal to a particle testing time tx, closing a valve B7, switching to a three-way valve 4 to enable the particles to go through a downcomer8, and closing a valve A5; and (c) taking down the collecting tank 6 to weigh and record a particle weight, thus calculating the particle distribution. By adopting the above technical scheme, the above technical problem is well solved; and the method can be used for measuring the particle distribution of the fluidized bed heat exchanger.