Spending too much time on mobile phone， tablets and other mobile devices has become a very common phenomenon. In this paper， the screen spectra of different types of mobile phone and computers are collected by using optical fiber spectrometer and the intensity with the distance was studied as well. The result shows that the spectral emission bands of the electronic display screen are mainly on 450 nm， 530 nm and 590 nm. The intensity of blue emission varies with types of products，which means the damage of blue light to the human eye is different with products.