A synthetic hydraulic oil is developed and all its indexes meet, even exceed, the requirements in GB11118.1-94 L-HS (quality products) criteria. Performance features and all technical indexes of the oil are described in the article. Its adaptability to the hydraulic systems in construction machinery is especially pointed out. A synthetic hydraulic oil is developed and all its indexes meet, even exceed, the requirements in GB11118.1-94 L-HS (quality products) criteria. Performance features and all technical indexes of the oil are described in the article. Its adaptability to the hydraulic systems in construction machinery is particularly pointed out.