Round bamboo has drawn more and more attentions in architecture, decoration and recreational products. Splitting brings some safety problems, which shorten the service life of Round bamboo. In this paper, three schemes were adopted as follows to solve the problem: Round bamboo was impregnated in PEG-1000 solution alone, heat-treatment in paraffin alone, or treated with the combination of PEG impregnation and paraffin heat treatment (PEG-PH). The treated bamboo was exposed outdoor for 26 weeks to evaluate the development of cracks. Results showed as follows: The initial split of PEG-PH treated bamboo appeared after 22 weeks, while that of the controls after 2weeks, respectively. the total length of cracks were 2271.31 mm and 873.5 mm for the control and PEG-PH treated bamboo. To reveal the reasons for reduced cracks, scanning electron micrograph (SEM) were employed to observe the microstructure of bamboo, besides, hydrophobicity of bamboo was characterized by water contact angle (WCA). PEG can swell the cell wall and the better hydrophobicity of round bamboo could be achieved after PEG-PH treatment. Therefore, the combination of PEG immersion and paraffin heating is an effective and practicable method in bamboo treatment, especially for round bamboo with high moisture content.