A diameter and density distribution analyzer of scanning nozzle atomizing fog drop is used in measuring instrument technical field, comprising programmable guide rail support, two microadjustment bearer, particle diameter and density optical sensor, A/D converter and computer. The particle diameter and density optical sensor is of isolating construction and consisted of transmitting terminal and receiving end which are installed on microadjustment bearer fixed on programmable guide rail support, electro optical signal 10 collected by transmitting terminal and receiving end is transferred to receiving end of A/D converter from which digital signal is transferred to computer. The invention is mainly used in atomizing field research of various nozzles, without special requirement to work medium of atomizing field, and it can even be used to measure special distribution of solid state particle diameter and density in jet stream with gas and solid two states, its has large sampling area, small measurement error of density, its measuring course is easy to be automation and experimental measurement period is short.