Based on LabVIEW platform, a virtual instrument which can simulate process of Franck-Hertz experiment is developed.The virtual Franck-Hertz experiment instrument can simulate all the operation of the real instrument ,set parameters, give the 1-V value,and on the other hand recording data and drawing at the same time.We use the Monte Carlo method for the physical process of the experiment.The Franck-Hertz tube is divided into segments according to the flat free path of electron collision with argon atom, and the motion process of electron is simulated.Thus,the I-Vcharacteristics of Franck-Hertz tube are given.Because of the great amount of numerical simulation,real-time simulation of Monte Carlo algorithm based on the Labview is too time consuming to achieve.we save severa sets of real franck-Hertz experiment data. then mix them according to the parameters to simulate a Franck-Hertz experiment of measurement process,the result is well agreed with the real process.