This invention relates to environmentally friendly diesel oil, which is composed of: diesel oil 13-20 parts, water 15-30 parts, plant oil 20-25 parts, methanol 8-11 parts, kerosene 10-30 parts, and composite additive 5-8 parts. The composite additive is composed of: triton X-100 2.0-2.65 parts, ethanolamine 1.5-3 parts, NaOH 14-16 parts, 99.5% ammonia solution 50-55 parts, n-butylamine 5.0-6..0 parts, isopropane 18-21 parts, water 2.0-2.3 parts, and cetane 0.2-1.0 parts. The environmentally friendly diesel oil is prepared in a raw material tank, an aid tank, a product tank, a sealing device, a high-energy static magnetic device and pipelines. This invention solves the problems of low stability, easy separation of oil and water, large amount of emulsifier, high price and difficult transportation faced by present W/O emulsified diesel oil, and has such advantages as abundant raw materials and wide applications.