There are general definitions of category 334 resources in “Classification for Resources/Reserves of Solid Fuels and Mineral Commodities” and “General Repuirements for Solid Minerals Exploration” promulgated by the Chinese authorities. This paper attempts to undertake the resources estimates by using the data collected from the Bailashui tin ore district as an example, the categories 333 and 334 resources estimates are discussed. It is proposed that the category 334 could be divided into 3341 and 3342, and for the categories 333 and 334 resources estimates, the level of confidence, orebody delineation rules, the resources code, the industry parameters and proportion of resources and reserves etc. are discussed.