Objective Direct amplification of length polymorphism (DALP) as a new molecular marker was used to establish a set of stable DALP reaction system for the plants of Rhodiola L. Methods Some significant parameters of DALP reaction procedure were investigated and optimized by taking the DNA genome for the plants of Rhodiola L. as template. Results The reaction system was : 20 ?L reaction system containing 2. 5 mmol/L Mg2+ , 1. 25 mmol/L dNTPs, 60 ng DNA template, 1 ?L 5 pmol/L selective primer, 3 ?L 5 pmol/L reverse primer, selective primer: reverse primer is 1 : 3, and 2 U Taq DNA polymerase. Amplification program is 95℃ pre-denatured for 5 min, 94℃ denatured for 30 s, 50℃ annealed for 30 s, 72℃ extending for 1 min; after 30 cycles, and then 72℃ extending again for 10 min to the end of PCR reaction. Conclusion This DALP reaction system is efficient to identify the species and local populations for the plants of Rhodiola L. repeatedly with the stronger stability and reliability.