We, herein, indicated for the first time the Rnase activities of LbCas12a on linear ssRNA above 11 bases, and hairpin RNA substrates. Meanwhile, the LbCas12a bound to ssDNA or ssRNA exhibited different cleavage efficiencies on various substrates, including short ssDNA, hairpin DNA, linear ssRNA and hairpin RNA. With hairpin DNA as a reporter, we attained a detection limit of 5 pM and 50 pM for the ssDNA and ssRNA targets, respectively. We believe that these findings will pave a new avenue for expanding the reporter toolbox for Cas12a-based diagnostics in biosensing and biochemistry.