The high speed railway in China has already been the longest one around would.The damage on rail surface is one of very serious troubles in the high speed railway.It is impossible for a man to inspect the damage along a rail track of 1000 kilometers a day.Most of the inspection systems for the damages are that a camera on train catches the images as the train is running.But a computer on the ground is used to analyses these images caught by a camera after the train come to home.It is necessary to have a detection system to find the damages in-line as the train is running.An automatic high speed in-line system on the train for detection of damages on rail surface has been constructed.It is a vision system with a computer, in which a smart algorithm for the processing images of rail surface is coded.It works in a train with a speed over 200 km/h.The Detection system can automatic detection of damages on rail surfaces, like flakes, cracks, grooves or break-offs, et al, in the size of 2mm*2mm and give alert when the damage is found in a high speed train.It has been tested in the railway between Guangzhou and Zhuhai cites.We will report our systems, including apparatus, algorithm, and software.The experiments and tests in laboratory and on railway are introducing as well.