Objective To build a gene chip that is used to simultaneously detect the constant gene mutations of β-thalassemia and achondroplasia quickly and exactly.   Methods Specific aminated oligonucleotide probes based on the constant gene mutations were fixed on the aldehyde modified glass. The gene chip was made. The blood sample from 3 children with β-thalassemia and from 3 children with achondroplasia and 6  normal subjects was used to diagnose β-thalassemia and achondroplasia by the gene chip.   Results The gene chip successfully detected the certain mutations.   Conclusion The low-cost chip is of well-repeated and high specificity in checking clinical samples.