Abstract: In order to realize uniform coating of photoresist on large area substrates, a small meniscus coating applicator is designed and assembled, and it is used to coat a substrate of 200 mm200 mm. Then a thickness measurement system based on white light interference spectrometer is installed to measure the thickness distribution of the coated photoresist, the result shows that the peak value of the deviation is less than 5%. Thickness uniformity is analyzed for further optimizing the coating system and coating parameters. Finally the accuracy of the thickness measurement system is tested by comparing the measuring results with that of a surface profiler which has very high resolution and has been calibrated, and the deviation is less than 0.8%.