The invention discloses a preparation method of a conductive PP (polypropylene) thin film with a low percolation threshold and high mechanical properties. The preparation method comprises steps as follows: PP aggregates are put in a melt-blowing machine for preparation of PP fiber webs through melt-blowing; conductive particles are dispersed in a xylene solvent and subjected to ultrasonic oscillation, and a solution A is prepared; the PP fiber webs are placed in the solution A and subjected to the ultrasonic oscillation for 2-5 min, then the PP fiber webs are taken out, washed and naturally dried, and conductive fibers are obtained; the conductive fiber webs are divided into an upper layer and a lower layer and are laid on templates of a press device, a few PP aggregates are placed between the fiber webs and subjected to hot pressing in a vacuum press for 10-15 min, and the conductive PP thin film with higher comprehensive mechanical properties and the lower percolation threshold is obtained. The ultrafine PP fiber webs prepared with a melt-blowing technology have large specific surface area, surfaces of the fiber webs are uniformly modified with conductive filler with an ultrasonic dispersion method, a uniform conductive network structure is formed in the film after hot pressing, the technology is simple, and the prepared conductive thin film has both the higher mechanical properties and the lower percolation threshold.