Solar radiation distribution on vinyl film greenhouse floor was clarified using a light analizing model. Observed shortwave radiation in outside was divided into direct and diffuse radiation components. Diffuse radiation was separated into 36 pieces of small suns in the hemisphere. Greenhouse walls were assumed to be composed of 10 pieces of flat film. Transmission, reflection and absorption rates on each walls were determined calculating the angle between wall and incoming radiation. The calculation of diurnal change of shortwave radiation showed good agreement with the observed data. Daily total radiation on floor was 10% higher than observation. The daily radiation in east-west oriented greenhouse was slightly higher than north-south oriented house. Radiation at center was higher than the surrounding spots. To improve the accuracy of the model, it is neccesary to take into account the changes of optical characterisics of vinyl film. The calculation of succesive reflective radiation on vinyl films must be taken into account, also.