The invention discloses an object space telecentric optical imaging system with a long object distance, and relates to the field of optical imaging. The system sequentially comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a seventh lens from an object side to an image side along an optical axis, the focal power of the first lens, the third lens, the fourth lens, the fifth lens and the seventh lens is a positive value, and the focal power of the second lens and the sixth lens is a negative value, wherein-0.51 < f1/f <-0.36, 0.45 < f2/f < 0.63,-0.66 < f3/f <-0.49,-0.18 < f4/f <-0.07,-0.10 < f5/f <-0.05, 0.05 < f6/f < 0.06, and-0.04 < f7/f <-0.02, and f is the focal length of the object space telecentric optical imaging system, and f1, f2, f3, f4, f5, f6 and f7 are focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens in sequence. The method has the advantages of long object distance, high object space telecentric degree, low distortion, large depth of field and the like.