This book concerns to research how war influences any countries' economy development. In Part one, chapter one concerns what international war influences. I shall explain whether wars can impact economy threat. I shall indicate how First World War influenced Europe economy; what US economic consequences of war are; how can economy policy influence peace and security; What relationship is between civil wars and economic growth; how economic impact of the war and higher military spending is. In part two, chapter two concerns the country's internal civil war, I shall explain what the relationship is between internal war and human welfare. I shall indicate how internal war influences human welfare; whether internal civil wars can influence the country's long run economic development; when and how can be stopped the civil internal war to influence economy growth. In my focus, I shall give my opinion to solve this question: Whether do wars bring either advantages or disadvantages or both to impact our economy growth ? I write this book aim to give my opinion to let readers attempt to find answers to judge whether international war or country internal civil war will influence economy to be worse.