The invention discloses a construction method for controlling the cleanliness of an electronic-grade multicrystal-silicon process pipe. The construction method comprises the following steps of: (1) prefabrication machining; (2) pipe section assembling: finishing an assembly procedure of pipe sections by utilizing an interior gas protection device and an argon arc welding machine; (3) pipe section cleaning comprising the following steps of: degrease cleaning, water flushing after degreasing, complexing and derusting, rinsing, ammonia-plugging flushing, passivation processing, ultra-pure water flushing, dry processing and packaging; (4) multicrystal-silicon process pipe assembling; (5) field assembling of the multicrystal-silicon process pipe; and (6) process pipe blowing, pressure testing and airtightness testing. The invention has the advantages of reasonable design, simplicity and convenience in operation, convenience for realizing and good pipe cleanliness control effect, can solve various problems such as complex factors influencing the cleanliness of the interior of the multicrystal-silicon process pipe, difficulty in control of the cleanliness of the interior of the pipe, poor control effect of the cleanliness and the like in a multicrystal-silicon process pipe construction process.