Experimental observations and numerical simulations were conducted on combustion processes of n-decane polydisperse spray entering gaseous flat-flame stabilized in laminar 2D counterflow configuration. The experimental burner restrained the flow from fluctuating to investigate the effects of spray characteristics. Concerning the calculations, for the gaseous phase, we used Eulerian mass, momentum, energy, and species conservation equations. For the disperse phase, all the individual droplets were tracked without using a droplet parcel model. Firstly, we observed blue and luminous flames experimentally and the intensity of these flames changed unsteadily. Secondly, we examined the spray flame structure numerically should the supplied quantity of liquid fuel changed. Both timeaveraged and instantaneous spray flame structures varied depending on the quantities of spray. Furthermore, the instantaneous structures were consistent with the typical flame structures observed by the experiment. Consequently, these results show that the difference of the supplied liquid fuel spray can cause the variation of spray flame structures.