The Data Logger is an important secondary-instrument,which can be applied to automatic monitor and control system,and high speed local data acquisition for later analysis.The Virtual Great Capacity of Data Logger based on virtual instrument technology is a new instrument which has more advantages than the traditional Data Logger.The design method has been introduced from three ways,which includes system principle, hardware configuration and programming design, and an application example is given.This Data Logger is low cost,easy to take,also easy to operate.It can be widely used in many of actual applications.