The present invention relates to a composition in the form of an oil-in-water emulsion comprising a combination of at least one particular nonionic surfactant and of at least one specific fatty substance in a particular weight ratio and at least one propellant. The invention also concerns an aerosol device containing said composition, and also to a process for the cosmetic treatment, notably for the styling, of keratin fibres, in particular of human keratin fibres such as the hair, using said composition.