We have examined the possibilities of ground-based optical observation system for LEO objects. Space environment is deteriorated with space debris especially in LEO region in recent years. The accuracies of TLEs are not good enough for the collision avoidance. Optical sensor has an advantage of being able to determine the positions of space objects in arc second's accuracy which will contribute the precise orbit determination and cope with the situation. The array of numerous optical sensor may be equivalent to the a radar observation system which is common for LEO observation. Although observable time for optical sensors are limited to 4-6 hours per day, the cost is much less than that of radar system. We carried out some simulations to evaluate the optical system. The simulations have shown that identical objects were recognized from the data of 4 individual equipments installed on 2 separate sites using the orbital elements of each object. This enables us to determine orbits of un-catalogued LEO objects precisely.