In order to make full use of the resource of earth observation satellites and acquire higher quality scenes,a multi-objective grey ant colony system was proposed.Firstly,the interval grey was used to describe the cloud cover above the area of an imaging task.Then a multi-objective optimization model of the earth observation satellites was built with the consideration of the importance of imaging tasks and their quality.Finally,the grey theory and ant colony system were combined with the rule of updating by region and the spirit strategy to improve the diversity and the convergence of Pareto optimal set.The experimental results show that the proposed system can solve the scheduling problem for multi-objective earth observation satellites effectively.