A 1.5L turbocharged direct injection gasoline engine was used to study the performance of different NOx after-treatment methods in lean burn gasoline engine with different combinations of three-way catalytic (TWC)

lean burn NOx trap (LNT)

passive selective catalytic reduction (PSCR). 14 operation conditions were selected according to worldwide harmonized light vehicles test cycle（WLTC）. The results show that lean burn can effectively reduce the effective fuel consumption of gasoline engine by 3.1 ~ 10.1% under part load. In lean burn

the proportion of NO in total NOx decreases by 6.9% for every 0.1 increase of lambda. In rich burn

for every 100 × 10-6 increase in NO volume fraction before TWC

NH3 increases by 48 × 10-6. The NO-NH3 conversion rate of TWC ranged from 51% to 74% at lambda 0.95. TWC + LNT + PSCR can effectively improve the lean burn operation time. In lean burn

LNT can promote the oxidation of NO to NO2

increase the ratio of NO2，improve the catalytic efficiency of PSCR.