No, your Pekingese doesn't NEED a haircut. As the proud parent of a Peke, you get to decide whether your shaggy little pet needs a haircut -- there are no rules unless you are planning to enter your champion in the show ring.
Do You Have the Time?
If you fell in love with him because of the traditional thick, flowing coat that is characteristic of the breed, or if you plan to show him, be aware that daily grooming and special grooming tools are required to keep up the health and appearance of the coat. The Peke coat has two layers: a long, coarse outer coat and a soft, dense undercoat. Your tool kit will include at least three brushes, a metal comb, grooming spray and talcum powder. You might spend more time on his hair than yours. You will spend at least an hour -- daily -- spraying, brushing and combing your Peke, turning and flipping him from one side to the other.
Shedding and Dirt
Your hairy little girl will shed -- on the rug, on the furniture, and on your bed -- if you don't get her hair cut. She'll shed less if you groom her by brushing and combing through both layers of hair right down to her skin at least once a week. In addition to shedding, her long, flowing coat will attract debris like a magnet. A quiet walk through nature will yield a collection of dead leaves, grass and twigs clinging to the bottom of her coat and the feathers on her legs.
Comfort and Health
Your little one's health and comfort should come first. The health section on the Pekingese Club's website points out that in hot weather, the thick-coat-wearing Pekes are likely to become overheated. This puts them at risk of heatstroke; their tiny noses make it difficult for them to pant enough to cool their body heat. Unless you can provide cool air in hot weather, a haircut would help. A haircut also would make it easier to control itching from fleas and skin allergies.
Best of Both
If you're not showing, you can have it both ways with your Peke -- short hair in spring and summer, and long, full coat in fall and winter. In late spring, take him to the groomer and get a "puppy cut" style where the hair is trimmed short on the body, ears and legs. It's easy to maintain and it'll help keep him cool on hot summer days. As fall approaches, let his hair grow out and he will have a warm winter coat.