The　feature　of　ultrafiltration　to　remove　particle　matters　is　introduced　in　this　article.　It　is　pointed　that　particle　contents　are　key　monitoring　and　control　index　to　ensure　treated　water　quality　of　membrane　filtration.　Particle　monitoring　techniques　are　briefly　illustrated　and　the　application　features　are　analyzed　with　several　particle　monitoring　techniques.　Correlations　of　turbidity,　particle　counting　value,　multiple　index　of　particle　and　microbe　index　are　studied　and　analyzed.　The　results　show　that　particle　number　is　the　key　monitoring　indicator　of　treated　water　quality　of　ultrafiltration.　It　is　suggested　that　the　particle　index　can　be　applied　to　replacing　or　replenishing　turbidity　index,　and　particle　monitors　can　be　utilized　to　replace　or　replenish　turbidity　meters　to　monitor　and　control　operation　of　ultrafiltration　equipment　in　practical　applications,　in　order　to　provide　safety　to　effective　operation　of　ultrafiltration　and　production　of　high-quality　water.