Abstract: A new method--β-dichannel deduction method for the determinationof strontium-90 in the solution containing strontium and'yttrium is described. The content of strontium-90 in the solution can be determined rapidly by ordinary 'detectors and instruments without chemical treatment, with no interference from yttrium-90. This method is suitable for on-line determi-nation of strontium-90 in the process for the purification of strontium-90.