The win snaps the Brewers' three-game skid.
Braun hit a solo shot and Kevin Mench a three-run drive in a four-run first inning against Mike Bacsik (2-6). Milwaukee has homered in 15 consecutive games, its longest streak since a 19-game run in 1996.
Bush (7-7) improved to 4-1 in his last five starts. The right-hander went seven innings, allowing one run and seven hits. He walked two and matched a season high with seven strikeouts.
Ronnie Belliard homered and had four hits for the Nationals, who have dropped nine of 11.