Can I know what command are used to read the output in XBee 900 HP in Matlab ?

I think you are asking what is the correct command for MATLAB to read the serial port is that correct?

Yes, you are correct. Do you have an experience doing it ?
(Sorry my english are bad)

I am sorry but I don’t. But your Help files for MatLab should have information on how to send and receive data over a COM port. If not, I know there is lots of information on various news groups as well as Mathlabs web site on how to do this. My quick search I did came back with more than 220,000 sites.