Abstract:The in situ PCR technical system on chromosomes of Hevea brasiliensis was developed successfully. The HbMyb1 gene related with Tapping Panel Dryness (TPD) resistance was physically located in the long arm of chromosome No. 5 of ‘Reyan 7-33-97’ by in situ PCR and the fraction-length, the percentage of the distance from detection site to the centromere, was 15.21. One or two signals were detected during cell division at different phases. The chromosome preparations, preservation, and pretreatment were also discussed.