A low-power method for media access control on a semi-linear sensor network with multiple sensor nodes, includes: sensing a channel after waking up from a sleep mode by an arbitrary transmission sensor node that has obtained data; and generating a long preamble including a number of element preambles and sending to a destination sensor node after said channel sensing. This method further includes: sending said data to said destination sensor node after completion of transmission of said long preamble; and identifying duty cycle information of said destination sensor node after completion of transmission of said data and adjusting the number of said element preambles according to said duty cycle information.