Background Chitinase 3-like 1 (CHI3L1) plays an important role in airway inflammation and tissue remodeling; however, its pathogenic role in lung diseases remains unclear. In the present study, we investigated whether CHI3L1 polymorphisms are associated with the risk of chronic obstructive pulmonary disease (COPD) and asthma in a Chinese population. Methods We detected seven single nucleotide polymorphisms in CHI3L1 among 361 patients and 527 age- and sex-matched control subjects. We analysed genotype and allele distributions using Stata software (StataCorp,CollegeStation,TX,USA). We used haplotype disease analysis and haplotype phenotype analysis to assess the relationship between seven polymorphisms and the risk of COPD and asthma. Results The results showed significant differences between controls and patients with COPD/asthma in the genotype distributions of the polymorphism rs4950928. Additionally, significant differences were observed in the genotype and allele distributions of rs10399805 and rs10399931 between COPD patients and controls. Moreover, the frequencies of haplotype G-G-T-G-T-C-G, G-G-T-G-T-C-C and G-A-T-G-T-C-G (alleles of rs12141494, rs7542294, rs880633, rs10399805, rs10399931, rs946261 and rs4950928, respectively) were significantly higher in patients with COPD. Consideration of the haplotypes of these seven single nucleotide polymorphisms in CHI3L1 in asthma patients revealed a significant association with homocysteine levels (p < 0.001). Conclusions Our findings suggest that the CHI3L1 polymorphisms rs4950928, rs10399805 and rs10399931 can be used as genetic markers for predicting COPD and asthma risk in the Chinese population.