Objective To establish a field experimental research method to evaluate air transmission ability of respiratory infectious diseases. Methods The simulated saliva containing Escherichia coli phage was atomized in a typical mechanical ventilation ward, atomized droplets and cough droplets had droplet spectrum of similar droplet size distribution, the number of droplet nuclei with different particle size in air was detected, geometrical dimension of the initial droplet was estimated, the number of phages initially carried by droplet nuclei was calculated, the actual survival of phages in the droplet nuclei was obtained by collecting biological specimen of air, survival function of phage carried by droplet nuclei in ward air between two groups of data was compared. Results The number of viable phages carried by simulated atomized saliva droplets rapidly lost about 83% under surface evaporation, the average survival function of phage in the droplet nuclei was stable at 17% and did not change with the detection point during the detection period of 360 seconds, attenuation rate of the number of droplet nuclei in indoor air was consistent with that of phages in air specimens, biological exposure level of the ward space can be calculated by recording the number of atomized droplet nuclei. Conclusion The artificial simulation technology of virus transmission in the air induced by cough droplet nuclei can be applied to evaluate field experiment of the air transmission ability of respiratory infectious diseases.