京郊中棚西瓜始现于1990年，是在小拱棚双覆盖的基础上发展形成的种植方式。采用此方式后，京郊正常年份西瓜上市期较原来小拱棚地膜覆盖（6月24日至7月15日）提前20～30天。中棚的结构和大棚相比具有造价低、易拆建、适应性强的特点，比小拱棚明显早熟、高效益，更具科学化现 The suburban watermelon in the suburbs of Beijing was first introduced in 1990, and was developed on the basis of double coverage of small arch sheds. After adopting this method, the listing period of watermelon in the normal suburbs of Beijing suburb is 20-30 days earlier than the original small arch shed filming (June 24-July 15). The structure of the shed and the greenhouse compared with a low cost, easy construction, strong adaptability than the small shed significantly precocious, high efficiency, more scientific and now