The invention discloses a detection method for a core installation position during sand casting. The method comprises the following steps: manufacturing a detection apparatus according to the correct position of a main body core in a lower sandbox, installing the main body core in the lower sandbox and clearing floating sand of the lower sandbox; and disposing the detection apparatus on the lower sandbox, fixing the detection apparatus with the lower sandbox by using a positioning fixed part and detecting the installation height and the installation planar angle of the core by using the detection apparatus. With the detection method provided by the invention, the possibility of occurrence of insufficient casting of castings and out-of-tolerance of a size is reduced, the qualified rate of a product is increased, the castings are allowed to have stable sizes and improved internal metallurgical quality, a casting period is effectively shortened, and production cost for the castings is saved.