The invention is suitable for the field of sensing monitoring, and provides a laser PM2.5 sensor packaging device and an automobile. The device comprises a shell, an end cover and a fixing sponge, an opening is formed in the top part of the shell and is used for placing a laser PM2.5 sensor, an annular air flue allowing air to flow through is reserved between the side surface of the sensor and the side surface of the shell, an air inlet and an air outlet of the sensor are both located on the annular air flue, a horizontal baffle plate is arranged on the side wall of the shell right above the air inlet, the length of the horizontal baffle plate is less than the horizontal width of the annular air flue, the end cover is arranged at the top part of the shell, two vent holes are respectively formed in the two sides of the top part of the end cover and are communicated with the annular air flue, a groove is formed in the inner surface of the top part of the end cover, the fixing sponge is arranged between the groove of the end cover and the sensor, the end cover extrudes the sensor through the fixing sponge, air suction airflow is buffered by the annular air flue and limited by the baffle plate if the air flow in the environment abruptly changes, so that air inflow of the air inlet is not fluctuated obviously, thereby being favorable for the stability of the detection performance of the sensor.