Objective  Based on the “Work Plan for Cultivated Land Resource Quality Classification” drawn up by the Third National Land Survey, this research discussed the quality classification and grade conversion methods of cultivated land resources in Beihai, Guangxi Province. The results would provide a reference for practical applications such as balance between occupation and compensation as well as entry and exit about cultivated land through conversion into grades.

  Method  The basic data through field inspection and interpret the relevant results of the second soil census were update, and the evaluation parameter system was adjusted for the local area updated the results of the quality of cultivated land. The classification of farmland resources quality in Beihai was evaluted and the classification results by statistics were obtained according to technical requirement. The Yinhai district of Beihai was selected to conduct empirical research and discuss the rationality as well as the advantages and disadvantages of the conversion methods based on three sets of grade conversion methods.

  Result  The conversion result of the assigned points method was reasonable and better reflected the quality difference and distribution of cultivated land resources, but it was not comparable across the country. The distribution of the graded results produced by the permutation and combination method was unreasonable, and the results were easily affected by low-level indicators. The conversion result of the grade-addition method was more reasonable, which was convenient to achieve national comparability of the cultivated land quality, but the conversion results had a low grade span, and the difference was not strong.

  Conclusion  The conversion method of grade points and sum method can meet the national comparability of cultivated land quality, and other comparable conversion methods need to be explored.