The ground state entanglement of the XY Heisenberg model of open spin-1/2 chains in one dimension was calculated and analyzed. The ground entanglement of this model was worked out by the method connecting the entanglement defined by von Neumann entropy with the ground eigenvectors. N is the total number of sites, k is the number of electrons at site spin up ， andηis the ground entanglement. The conclusions are as following. (1)ηincreases when N is same and k increases;ηdecreases when k is same and N increases. The result embodys relevancy of the system. (2)ηis always 1 when N is even and the situation is [N, N /2]. The result embodys the rigid symmetry of the numbers of electrons at site spin up and down. (3)ηis different along with the changes of the parameters of model. (4) The system has continuting and long-range phase, and the quantum phase transition of the system is order to order.