Gene detection has become an important issue in predictive medicine,disease prevention,health management,and personalized medical services.[1] The development of a versatile biosensing platform to screen specific DNA sequences is still an essential issue of molecular biology research and clinic diagnosis of genetic disease.[2] In the present study,a Multiply-branched rolling circle amplification(MB-RCA)was proposed for enhances detection sensitivity of cancer Kras gene codon 12.The system primarily consisted of a padlock probe(PP)and a structurally tailored molecular beacon(MB).The important aspect of this MB is that,it can be opened by Kras gene and triggers molecular machine operation generating a long tandem single-stranded DNA(ssDNA)product.