Abstract: The present paper deals with the spatial distribution patterns and sampling technique of Polychrosis cunninghamiacola which were carried out in Sha county and the suburbs of Sanming city, Fujian province from 1984 to 1985. Frequency chech methods and several aggregation indices were used to determine the spatial distribution patterns. Most larvae and pupae were of aggregated patterns. The optimal sampling sizes were determined. Five sampling methods were compared and the ones most suitable for the investigations of larvae and pupae were suggested. The equations based on the relationships between percentage of the trees with larvae or pupae and the numbers of larvae or pupae per 100 trees were built up, they can be applied to practical investigations.