The "Janenope" diesel fuel pre-filter was jointly researched and developed by Xi'an Tianhou Filter Technology Co., Ltd and America Boston Pre-filter Co.,Ltd based on the quality characteristics of the diesel fuel market in China. The device adopts multi-level integrated filtering technology, can filter more than 90% of tars, pitches and mechanical impurities in diesel fuel. Since the promotion of our diesel fuel pre-filter both at home and abroad 2 years ago, diesel engine malfunctions caused by diesel quality have been greatly reduced, moreover, notable economic benefit and social benefits have been achieved in the aspects of oil-saving, life-span extension of diesel engine and so on.