The invention discloses an ejection metering module for SCR (
selective catalytic reduction) and a controlling method of the ejection metering module. The ejection metering module comprises a support, a pulse pump mounted at one end of the support, an upper end cover fixed at the other end of the support, an ejection
nozzle and a controller, and is characterized in that the support extends from the upper portion of a DEF (
diesel exhaust fluid)
storage tank deeply to the bottom of the DEF
storage tank and is fixed on the
diesel exhaust fluid
storage tank via the upper end cover, the controller controls the pulse pump to work, the pulse pump comprises a solenoid driver, a
plunger pump and an internal flow passage which penetrates through the pulse pump axially,
working fluid (DEF) enters an inlet of the internal flow passage via a first filter arranged at the inlet at the lower end of the internal flow passage, an outlet of the internal flow passage is higher than the inlet of the same in arrangement, part of the
working fluid in the internal flow passage is pumped to the ejection
nozzle through the
plunger pump, and the other part of the
working fluid is drained from the pulse pump via the outlet of the internal flow passage. Characteristic parameters of the pulse pump are prestored in the controller, so that the ejection metering module is capable of working in a slave mode or an intelligent (master) mode.