I suspect that you want to calculate the mean pixel value of every band. If that is so you can you the Statistics tool. In ENVI 4.8 and Classic it is under Basic Tools > Compute Statistics. For ENVI 5: Toolbox, select Statistics > Compute Statistics If need something else please provide more details of the work you are doing. For future reference please tell us what version of ENVI you are using so we can quickly determine what needs to be done. You can always also refer to the ENVI Help for assistance as well.

Sorry for not provide more detail information. I am working with ENVI 4.5. You didn't catch my thought. I didn't want to calculate the every band mean value, i want to calculate every pixel mean value. So it means every pixel whole bands mean value. I hope you understand. I didn't find nothing about this in help! Skywalker