Since there are more and more satellites in the constellation, autonomous position determination by using single satellite has been gradually replaced by the whole autonomous navigation by using the inter-satellite relative observation in the constellation. Based on analyzing inter-satellite relative movement for Walker constellation, the resolution expression of the inter-satellite relative distance and the partial derivative with respect to orbit elements are presented firstly. The variation of orbit elements in the inter-satellite measurement is intuitively described in the same orbit plane and different orbit plane. Secondly, based on the relative position of satellites in the constellation, rational restriction and estimation method is put forward. The orbit determination of the whole network of the constellation is realized using the measurement of the inter-satellite distance. Finally, modified results of the orbit elements' system error and random error are compared in different instance using the rational orbit determination method by way of example.