This article examines feasibility of flame treatment for PTFE surface modification and compares effects with corona and plasma treatment. Feasibility: flame can modify PTFE but rarely used industrially — safety risks (PTFE decomposes releasing toxic HF and perfluoroisobutylene); performance limited (surface energy only 30-35 mN/m, forms weak boundary layer). Working mechanisms: flame — transient high-temperature oxidation (>1000°C), slight etching, few oxygen groups; corona — high-voltage discharge generates ozone/active oxygen, mild oxidation, low energy density cannot break C-F bonds; plasma — high-energy particles/electrons/free radicals directly cleave C-F bonds and graft polar groups (hydroxyl, carboxyl, amino).