A　planar　fractal　model　for　simulation　of　frost　formation　and　growth　was　proposed　based　on　diffusion　limited　aggregation　(DLA)　model　and　the　computational　simulation　was　carried　out　in　this　paper.　By　changing　the　times　of　program　running　circulation　and　the　ratio　of　random　particles　generated,　the　simulation　figures　were　gained　under　different　conditions.　A　microscope　is　used　to　observe　the　shape　and　structure　of　frost　layer　and　a　digital　camera　with　high　resolution　is　used　to　record　the　pattern　of　frost　layer　at　different　time.　Through　comparing　the　simulation　figures　with　the　experimental　images,　we　find　that　the　simulation　results　agree　well　with　the　experimental　images　in　shape　and　the　fractal　dimension　of　simulation　figures　is　nearly　equal　to　that　of　experimental　images.　The　results　indicate　that　it　is　reasonable　to　represent　frost　layer　growth　time　with　the　program　circulation　times　and　to　simulate　the　frost　layer　density　variation　during　its　growth　process　by　reducing　the　random　particle　generation　probability.　The　feasibility　of　using　the　suggested　model　to　simulate　the　process　of　frost　formation　and　growth　was　justified.　The　insufficiencies　and　its　causes　of　this　fractal　model　are　also　discussed.