Objective To identify the effect and mechanism of recombinant platanus pollen allergen 2 (rPla a2) on the transcription and expression of orosomucoid 1-like 3 (ORMDL3) gene in NIH3T3 cells. Methods Quantitative real-time PCR and Western blot analysis were used to detect the influence of rPla a2 on the mRNA and protein levels of ORMDL3 and GATA3. After transfection of GATA3 siRNA or pcDNA-GATA3, the role of GATA3 was evaluated in rPla a2 regulating ORMDL3 expression. Dual-luciferase reporter assay was performed to measure the influence of rPla a2 and GATA3 on ORMDL3 promoter activity. Results The rPla a2 induced mRNA and protein expressions of ORMDL3 and GATA3. Knockdown of GATA3 inhibited the induction of rPla a2 upon ORMDL3. In addition, the induction effect was enhanced by over-expression of GATA3. ORMDL3 promoter activity was significantly promoted by rPla a2 and inhibited by knockdown of GATA3. Conclusion The rPla a2 up-regulates the expression of ORMDL3 mRNA and protein, which is mediated by GATA3 through targeting promoter region of ORMDL3.