Since the direct electron transfer of myoglobin (Mb) is hardly realized on the bare electrode, the electrodeposition of the mixture of novel MnO2-C composite microsphere, sodium alginate (SA) and Mb on the surface of the carbon ionic liquid electrode (CILE) was conducted to fabricate the modified electrode, denoted as Nafion/Mb-SA-MnO2-C/CILE. The biological activity of Mb in the Mb-SA-MnO2-C composite was confirmed by FTIR and UV-Vis absorption spectra. The fabricated Nafion/Mb-SA-MnO2-C/CILE exhibited a fast electron transfer process with a pair of well-defined redox peaks attributed to the excellent electrochemical property of MnO2-C composite microsphere and good biocompatibility of SA that could provide Mb suitable microenvironment to keep its biological activity and facilitate the electron transfer. Additionally, the modified electrode also exhibited a wider linear range and a low detection limit toward the electrocatalytic reduction in trichloroacetic acid with good stability, reproducibility and accurate detection for the real samples.