The utility model provides a spacing control ruler used for controlling building spacing. Three glass plates and a telescopic rod form a right angle trapezoid. Through movement and stretching of both ends of the telescopic rod on two glass plates which are used as upper and lower sides of the right angle trapezoid, the area of the space enclosed by the right angle trapezoid is changed. According to the building layout on a paper drawing, the area is changed into desired size. The spacing control ruler assists a designer to carry out judgment, so that whether spacing control is met a requirement can be intuitively and clearly reflected.