The invention discloses an oilfield sewage suspended matter content monitoring device and an oilfield sewage suspended matter content monitoring method, belonging to the technical field of oilfield sewage suspended matter content monitoring. The device comprises a sewage sample conveying pipeline, a washing water conveying pipeline, a filter, a vacuum pump, a spectrophotometer and a computer controlled center, wherein the sewage sample conveying pipeline is connected with the filter and the spectrophotometer respectively, the washing water conveying pipeline is connected with the filter and the spectrophotometer respectively, an electromagnetic valve and a flowmeter connected with the computer controlled center are respectively arranged on the sewage sample conveying pipeline and the washing water conveying pipeline, and the vacuum pump and the filter are connected. According to the monitoring system, the on-site sampling and on-site measurement in oilfield sewage can be realized, and measurement is completed in an entirely closed environment, and meanwhile, the obtained result is fast fed back so as to provide timely and accurate reference data for the technology adjustment. The oilfield sewage suspended matter content monitoring device and the oilfield sewage suspended matter content monitoring method are especially suitable for the real-time monitoring on the quality of water outflowing from a filtering tank to a wellhead.