With　the　help　of　accurate　parking　navigation　systems,　sharing　vacant　private　parking　spaces　with　public　travelers　may　have　the　potential　of　reducing　the　number　of　cruising　vehicles　and　contribute　to　traffic　emission　reduction.　However,　the　quantitative　effects　of　such　a　measure　are　still　relatively　unknown　in　traffic　management.　In　this　article,　we　firstly　established　an　optimal　allocation　model　of　shared　parking　spaces,　which　is　a　pure　integer　linear　programming　model　of　maximizing　the　number　of　served　public　vehicles　to　avoid　cruising　for　parking.　Further,　the　parking　space　allocation　model　was　expanded　to　an　estimation　model　that　quantifies　the　effect　of　emission　reduction.　Secondly,　a　branch-and-cut　algorithm　was　introduced　as　the　core　algorithm　to　solve　the　proposed　models.　Finally,　detailed　sensitivity　analysis,　based　on　empirical　data　collected　by　electronic　parking　toll　collections　and　questionnaire　surveys　in　Beijing,　China,　evaluated　the　proposed　model　and　algorithm.　The　results　indicate　that　shared　parking　can　not　only　effectively　reduce　the　cruising　time　and　the　number　of　vehicles,　but　also　has　significantly　a　positive　effect　on　emission　reduction.　This　research　is　helpful　to　provide　theoretical　support　for　alleviating　parking　pressure　and　environmental　problems.