In this study, 14 inflorescence phenotypic traits were measured in 198 Macadamia (Macadamia spp.) germplasms. Methods including genetic diversity index, correlation analysis, principal component analysis (PCA), and cluster analysis were employed to systematically evaluate the genetic diversity of inflorescence phenotypic traits and characterize the inflorescence performance of different germplasm groups. The results showed that the genetic diversity indices of four qualitative traits ranged from 0.073 (peduncle color) to 1.436 (floret opening order). For the ten quantitative traits, the genetic diversity indices ranged from 1.914 to 2.081; moreover, all quantitative traits except for corolla diameter and floret density were distributed across grades 1 to 10, indicating rich genetic diversity. Correlation analysis revealed significant or highly significant correlations between most quantitative traits, except for three specific pairs: pedicel length and peduncle thickness, corolla diameter and pedicel length, and inflorescence density and peduncle diameter. Four principal components were extracted via PCA, with a cumulative contribution rate of 81.861%. Based on PCA scores, the germplasms were categorized into six clusters: long inflorescence-small flower type, few-large flower type, short inflorescence-small flower type, short inflorescence-large flower type, long-many flower type, and short-many flower type. Further comparison between Chinese provenances germplasms and Australian and Hawaiian provenances germplasms using orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed that corolla diameter was a common differential trait, indicating that Chinese macadamia germplasms have undergone certain phenotypic differentiation in inflorescence. This study provides a theoretical basis for the evaluation of macadamia germplasm resources and the selection and breeding of pollinator varieties.