In 2017，the Chinese economy enjoyed a strong momentum of steady growth，and GDP growth proved higher than expected. With the creasing optimization of our country’s economic structure，the contribution of service industry to economic growth was becoming more and more prominent as well as the contribution of consumption to the growth of GDP kept rising. In addition，the quality and benefit continued to improve. Based on the analysis of the economic situation in 2017 and the related data of the earlier years，ARIMA model is built to forecast the economic and social situation in 2018. The results show that：in 2018，the GDP growth rate would slightly drop to 6.6%；investment would maintain medium-to-high growth，in particular，slow growth of private investment ought to be attached great importance；the growth rate of final consumption expenditure would achieve 11.74%，what’s more，online spending would perform outstanding；net export of goods and services might have large fluctuation；CPI would experience mildly rising；a slight drop of PPI could be seen in 2018. Economy decides public finance，so the judgement of the situation proves the basic of forecast of fiscal revenue and expenditure. By using ARIMA method，fiscal revenue would be still growing at a high speed，more over，the quality of fiscal revenue could enjoy further improvement in 2018. In fact，tax revenue could have fast growth，however，non-tax revenue is going to be further regulated. Indeed，rapid growth would be realized during excise tax、enterprise income tax、individual income tax and resources tax. Besides，VAT could go through a medium-high rate of speed when the positive effect of “business tax to VAT” as well as cumulative effect of making structural tax reductions and cutting fees across the broad is taken into consideration；the VAT and consumption tax of import goods might play slow growth. In 2017，the progress of fiscal expenditure proved accelerated. Furthermore，the level of budget management gained further improvement，and key expenditure is effectively guaranteed，especially the expenditure about people’s livelihood. Also，the poverty alleviation funds experienced huge growth. In the past years，the pulling rate of fiscal expenditure on GDP became stable. In other words，policy multiplier of active fiscal policy tended to decline. Because active fiscal policy would be held in 2018，as well as China would complete the building of a moderately prosperous society in all respects in 2020 and other elements，fiscal expenditure would maintain moderate speed. Also，the structure of fiscal expenditure would be further optimized. In addition，key expenditure would be effectively guaranteed. The results about fiscal expenditure show that：expenditure growth of social security would be 15.5%；science and technology expenditure、expenditure on agriculture，forestry and water affairs would maintain medium-to-high speed of growth；education expenditure，medical and health expenditure would gain slower growth，but the base of these has reached a larger level；transportation expenditure would be stable in 2018.