A total $k$-coloring of a graph $G$ is a coloring of $V(G)\cup E(G)$ using $k$ colors such that no two adjacent or incident elements receive the same color. The total chromatic number $χ"(G)$ of $G$ is the smallest integer $k$ such that $G$ has a total $k$-coloring. In the paper, it is proved that for any $K_5$-minor-free graph $G$, $χ''(G)\leq Δ(G)+2$ if $Δ(G)\geq 7$. Moreover, $χ"(G)=Δ(G)+1$ if $Δ(G)\geq 10$.