The utility model discloses a main shaft central hole detection device, which comprises a crawling device, a scanning device and an oil supply system for supplying oil to the main shaft central hole. The scanning device is connected with the crawling device through a connecting rod and comprises a scanning detection device and a rotation executive device for driving the scanning detection device to rotate, and the scanning detection device comprises a pneumatic supporting device and a pneumatic lifting probe. Compared with an original main shaft central hole detection device adopting a spring for supporting, the main shaft central hole detection device adopts the pneumatic supporting device, thereby being free of the influence of Hooke's law, capable of maintaining relatively constant supporting force in central holes with random diameters and convenient in operation of the crawling device. The probe also adopts the pneumatic lifting probe, namely, the probe is contacted with the inner wall of a central hole under the pneumatic effect, thereby being reliable in movement, simple and convenient and superior to a spring supporting probe. An oil supply way is simplified, an oil tank does not need to be installed, and an oil filling process is omitted, thereby not only saving a large amount of time wasted by oil tank installation, but also saving a large amount of machine oil for power plants, and reducing consumption cost.