Network on Chip (NoC) adopts the packages exchanging interconnection framework for communications on chip. The interconnection problem of NoC can be abstracted as a minimal spanning forest problem in Manhattan plane. A new algorithm based on obstacle avoiding rectilinear Steiner minimal tree by changing the edge weights is proposed for the connection, an optimization method for interconnection redundancies removing is also proposed. Experiments show that the total connection length for NoC is minimized. So the traditional bus communication framework's disadvantages, such as long global connect delay, weak signal integrity may be eliminated.