It is important to prune peach trees properly every year to keep them healthy and to promote fruiting. Peaches fruit on second-year growth so they need to grow well during the spring and summer to produce a good crop the following year.  Peach trees should be pruned in late winter. 

First, remove any dead or damaged branches, water sprouts and suckers. Then remove about one half of old, grey-colored branches. One year-old branches (which will be red-colored) can be cut back by about one half their length.  Remove most  horizontal, vertical and crossing branches. Aim to have about 4 or 5 main branches that grow out at about 45 degrees.

Always cut back just above an outward-facing bud. The resulting tree should be vase-shaped and open in the center to allow sunlight to enter.

Peaches tend to fruit heavily and so it's best to remove smaller fruits early in the season to produce a better crop of larger fruits later in the year.

Courtesy of NYBG Plant Information Service