Abstract: The concept of tree topology Bragg Optical Fiber Grating(BOFG) distribution sensing array is introduced.Comparing with the serrial topology array,this type of arrays has the following advantages.First,it is not necessary that the central reflecting wavelengths of all the BOFG sensors must be different.In general,they can be identical.Thus,the cost of producing the snesors can be cheaper and they will easily be commercialized;Secondly,for this type of arrays,it is likely that a large number of sensors can be employed and therefore it can be applied to large area real-time monitoring.Finally,because there is more than one optical path at the interface between the electronics and the monitored body the performance of antifailure will greatly be improved.The principle of the system construction is expounded buy a design example.According to the principle analysis and the typical parameters,the numerical results is presented and the performance of this array is analyzed.Meanwhile,some valuable conclusions are obtained.