Abstract: The paper analyzed trace quantity irrigation from five aspects including: reasons for irrigation, the source of irrigation water, crop demand for water, the role of soil during irrigation process, and functions of irrigation system. The author thinks that trace quantity irrigation is unable to meet the water requirement of crop in field at the demand peak because trace quantity irrigation system is unable to transport water to root zone of plant. During period other than peak demand, the water supplied by emitters of trace quantity irrigation system may be much more than that required by crops. In fact, trace quantity irrigation in Hami city is nothing but the subsurface drip irrigation with low flow rate, and results of the experiments showed that the flow amount of trace irrigation emitter was so small that it was unable to meet the water requirement of jujube trees, it did not have the self-adaptive ability, whose algorithms and experimental design were unreasonable. Theory and practice showed that the trace quantity irrigation with super low flow rate could not match with the water requirement of plant. This paper also explored the reasons why trace quantity irrigation could not achieve 'self-adaptive irrigation'.