The controlling card for light-emitting diode (LED) display screen is designed based on LPC1300 universal serial bus (USB) and USB device. From the content (including image and text) to be displayed, the host computer extracts the bitmap information. Lattice information is obtained by transforming the extracted information with an appropriate algorithm. Moreover, the host computer can set up relevant parameters of the controlling card, such as font size, font type, dynamic effects, and so on. The related information sent to the controlling card through USB. The controlling card reads and deals with the contents in the buffer,and drives the LED screen to display the contents.