[en] A combination of multiturn injection and RF stacking is proposed as an efficient beam injection method in storage rings for heavy ion fusion program. Five turn injection in each transverse phase space and four RF stackings give total stacking turns of 100 which is a result of compromizing the tolerable emittances and momentum spread in the ring. Space charge limit and coherent beam instabilities are investigated and it is found that the most severe limit is transverse coherent instability but it will be managed by the use of sextupole and octupole magnetic fields. Assuming a charge exchange cross section as 1 x 10^-15 cm², the e-folding life time is estimated at 180 ms, while the stacking time is 40 ms. (author)