Selection of qualified suppliers so-called "buy only wrong nothing wrong with selling." Purchasing fear is the wrong vendor. Therefore, one of the principles of procurement management is how to carefully select qualified suppliers, in order to establish equality and mutual benefit trading opportunities, maintain long-term trade relations of cooperation. Select the appropriate quality supply department to determine the grade and quality of the procurement of goods in accordance with the needs of plant personnel. In general, the principle of quality to fit the available, because good quality, not only purchase, consumption costs will be high, even wasteful use. On the contrary, the quality is poor, you can not use or too short, to increase the difficulties and loss of use. Such as the purchase toughness enough rope and so on. Select the appropriate time procurement time not too early and it is not too late. Early use of funds is caused by occupying storage area; too late have resulted in plant shutdown to be members, unnecessary losses caused by the company. Affect the company's reputation. In the "zero inventory" concept, timely procurement, timely arrival is the best mode of procurement. Select the appropriate price should be fair and reasonable price for the principle and avoid the cost of purchase is too high or too low. If the purchase price is too high, the company will make an additional cost burden, the loss of the finished pipe in the market competitiveness. Conversely, if the purchase price is too low, so-called "a sub-price goods", suppliers will be forced to cut corners, resulting in "cheap, poor quality", the production department can not produce qualified products, or increase consumption costs.