The method to construct pepper core germplasm based on phenotypic data was studied with 603 accessions which were divided into 5 groups by the fruit shape index.Four types of sampling proportion methods in group,six overall sampling scales and two sampling methods were compared by the phenotypic data of 28 characters.The main results were as follows:(1) The proportions of materials selected by proportional ratio,square root ratio,logarithm ratio and diversity ratio in primary core germplasm were 24.2%, 22.2%, 21.1% and 17.8%, respectively,which illustrated that the best proper sampling proportion within group was based on index of genetic diversity which enabled the sampled number or proportion from different groups tend to balance.(2) The index of genetic diversity (I) of the core germplasm established according to the method of genetic diversity index proportion reached maximum and the ratio of phenotypic retained (RPR) reached 98% when the over all sampling scale increased to 15%.Although the proportion of phenotypes retained,coefficient of variation (CV) and the coincidence rate of range (CR) all increased gently,the genetic diversity index of the preconcentrated core germplasm decreased accordingly when the overall sampling scale increased to over 20%.So 15% of the overall sampling sizes were more appropriate.(3) Using logarithmic ratio method and diversity ratio,under 15% of the total sample size,the I,RPR,CV and CR of the core germplasm constructed by cluster sampling were much higher than that by random sampling.(4) Based on the optimized sampling scheme,the core germplasm of 91 accessions of pepper germplasm were established.