The oscillatory motion encountered in a laminar spray flame as described in some experimental works is different from any reported previously in the literature. In the published works this phenomenon is associated with heat loss, droplet loading or gravity. In this paper a simplistic physical model for oscillations in the position of flame zone relative to the fuel nozzle is described. It is shown that this model is sufficient to demonstrate that the flame position instability may occurs due to some characteristics of the fuel stream warming at the entrance to combustion zone. An additional important advantage of this model is the easy possibility to graphical visualizes the effect of all of the flow properties and thermodynamic characteristic incorporated in the model.