In response to the difficulty of balancing environmental performance and temperature and salt resistance with traditional water-based drilling fluids，and taking into account the characteristics of deep tight oil horizontal well drilling，a set of environmentally friendly high-performance water-based drilling fluid system suitable for deep tight oil horizontal well drilling was developed based on the synthesized environmentally friendly temperature and salt resistant filtrate reducer SLP-2 and other environmentally friendly treatment agents，through the optimization of SLP-2 dosage and the selection of inhibitors and lubricants. The basic performance，settling stability，anti-pollution performance，reservoir protection performance，and environmental performance of the drilling fluid system were evaluated. The results showed that the system had outstanding temperature resistance performance. After aging at 180 ℃ for 16 h，the high temperature and high pressure filtration loss was controlled within 10 mL， which could meet the requirements of deep well operations. The system had strong inhibitory properties，with a rock debris rolling recovery rate of over 95%，which could effectively suppress formation mud making and wellbore collapse. The density control of the system was flexible and the settlement stability was strong. When the density reached up to 2.0 g/cm³，the density difference of the system was less than 0.2 g/cm³ and the settlement factor was less than 0.52. The lubrication performance of the system was excellent，and the lubrication coefficient was as low as 0.087，which could significantly reduce the wear and friction of the drilling tool. The system had strong anti- pollution ability. After adding pollutants such as 15% NaCl，1.0% CaCl₂，or 15% rock debris powder，the rheological parameters and filtration performance of the system remained stable. The environmental advantages of the system were obvious，the biotoxicity test showed that the EC50 value reached up to 75 600 mg/L（non-toxic level），and BOD5/COD ratio was 26.8%（easily biodegradable），and heavy metal content met industry environmental standards. This environmentally friendly high-performance water-based drilling fluid had been successfully applied in the CH-1 well，a deep tight oil-water horizontal well in the target block. The on-site operation results showed that there had been no complex accidents such as drill jamming or leakage during drilling. The performance of the drilling fluid was stable and controllable throughout the process，and the environmental indicators met the standards，achieving the goals of safe，efficient，and green drilling. It provides technical support for the drilling construction of deep tight oil-water horizontal wells and has good prospects for promotion and application.