Monolayer morphology of phase transitions and melting process of three low mass weight chiral liquid crystals have been studied and observed in situ by Brewster angle microscopy (BAM). The liquid crystals (LCs) have benzoate benzoyl or biphenyl groups as mesogens and undecenoyloxy as spacer and 2-methylbutyloxy as chiral end group. Their mesogens have different ester bonds in the chemical structure which lead to different bulk phase transition temperatures and gradual change of monolayer phase transition behaviors at the air/water interface due to the strong anchoring effect of the ester bonds with the water surface. Their phase transition behaviors have been discussed according to classical nucleation theory (CNT). Two-dimensional phase transitions for the molecules with multiple ester bonds via two growth process after initial nuclei is initiated: homogenous growth of single domains and coalescence of adjacent domains. Different sizes of the nucleus also indicates the progressive nucleation. Mm with the biphenyl mesogen has the highest transition temperature and the molecules formed aggregates even initially spread at zero surface pressure, the domains accumulated together to form a condensed monolayer during compressing. Melting process of the monolayers of MII and Mm have also been observed at constant surface concentration of molecules.