The invention provides a method for staining hard tissue slices using picrosirius red and application of method. The method includes the following steps: sampling from a silk tissue engineering ligament, fixing and coating the sample using resin, performing hard tissue slicing, detecting the secretion condition of types I and III collagen through picrosirius red staining. According to the invention, the picrosirius red is used to stain the hard tissue slices, so that the sample processing time is shortened, the operation steps are simplified, and the types I and III collagen can be directly observed on the hard tissue slices.