Preparation of the hexagonal Sr-ferrite powsers with high performance by co-spraying precusor of the FeCl$_2$+SrCO$_3$ at a low temperature was proved as a cost =-effective method. The co-spray roasting was carried out in the temperature range of 300~$700^{circ}C$ after SrCO$_3$ powders were mixed into 12FeCi$_2$.4$H_2O$ liquor. By this low temperature roasting method fine particles of multi-phased FeO$_2$+SrCO$_3$ were formulated. Powders calcined at 105$0^{circ}C$ for 1 hour show the best magnetic property of Mulcorner=69.96 emu/g, Mulcorner=36.98 emu/g, and ulcornerHulcorner=4.31 Oe. This calcining temperature is lower than that of the conventional dry method by 10$0^{circ}C$.