According to the structural characteristics of high-power dish concentrator mirror unit, and online installation process which need the mirror unit rapidly detection ,effectively regulation and accurately positioning.A mirror unit posture adjustment method was proposed which based on a trinocular vision measurement and auxiliary installation machine robots.Corner space coordinate equation of any mirror unit was established and mirror unit posture control system structure was designed, at the same time, the corresponding adjustment methods and steps were determined. Taken the 38 kW dish system as an example, the position of different mirror unit was calculated and the influence of the measurement error and manufacturing error was analyzed on the mirror unit . The result shows that the adjustment method which based on visual measurement,when do not consider the other error and the visual measurement error and manufacturing error Controlled within ±2 mm,can fit the adjustment precision requirements. of the mirror unit.