With calcium carbonate microspheres as template, pyrrole as precursor and graphite powder as padding prepared a ultrasensitive nano-porous pseudo carbon paste electrode (nano-PPCPE). Investigated the impacts of mass ratio of calcium carbonate microspheres and graphite powder on the electrode behavior. The results showed that with the calcium carbonate microspheres of size 60~80 nm as template, nano-PPCPEs surface area were up to 923.5 m2/g when the mass ratio of calcium carbonate microspheres/graphite powder was 1:1.5. Studied the nano-PPCPEs electrochemical behavior by the methods of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the results showed that the prepared electrode had good electrochemical behavior, high sensitivity, stability and reproducibility.