The utility model discloses a natural gas wellhead desanding device capable of judging the sand amount. The front end of a mixed gas inlet of the device is connected with a flange through a horizontal short connecting pipe. The upper end of the horizontal short connecting pipe is provided with a first pressure tapping opening. The upper end of a desanding device shell is provided with a second pressure tapping opening and a pressure relief opening. The first pressure tapping opening and the second pressure tapping opening are connected to a differential pressure gauge respectively through pressure pipes and pressure relief valves. The pressure relief opening is connected to a pressure gauge with a pressure relief function through a pressure pipe and a pressure relief valve. By means of the device, sand in a pipeline can be completely settled and filtered, scouring of the pipe wall can be reduced, and no fixed liquid will remain in the device; meanwhile, when to start desanding can be known, desanding can be started quickly, and the device can be switched off quickly and sealed tightly after desanding is completed; consequently, the sand can be removed accurately and quickly, and the device is prevented from being scoured by sand particles.