DHS Multiyear Acquisition Strategy Act of 2017 (Sec. 2) This bill amends the Homeland Security Act of 2002 to direct the Department of Homeland Security (DHS) to submit a multiyear acquisition strategy that allows flexibility to deal with ever-changing threats and risks and that helps industry align resources to meet DHS needs. Such strategy shall be updated and included in each required Future Years Homeland Security Program. The strategy shall include: a prioritized list of major acquisition programs that DHS and component acquisition investments seek to address, a plan to develop a reliable DHS-wide inventory of investments and real property assets to help DHS plan and acquire upgrades of its systems and equipment and plan for acquisition and management of future systems and equipment; a plan to address gaps between funding requirements for major acquisition programs and available resources, identification of capabilities required to support the acquisition of technologies to meet the needs of such strategy, identification of ways to increase opportunities for outreach to ensure that DHS understands the market to meet its mission needs, a plan to ensure competition for major acquisition programs, and an acquisition workforce plan. The strategy also shall include assessments of ways DHS can: improve its ability to test and acquire innovative solutions to allow needed incentives and protections for appropriate risk-taking; develop incentives for program managers and senior DHS acquisition officials to prevent cost overruns, avoid schedule delays, and achieve cost savings; and improve the acquisition process to minimize cost overruns. (Sec. 3) The Government Accountability Office shall review the strategy to analyze its effectiveness in meeting specified objectives.