Danny Green has the highest plus/minus for the Raptors in a season, at +638 in 2018-19.

highest plus minus in a season by a raptors player

NAME	+/-	SEASON	TM	GP	MPG	PPG	RPG	APG	SPG	BPG	TPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	MIN	PTS	REB	AST	STL	BLK	TOV	PF
Danny Green	+638	2018-19	TOR	80	27.7	10.3	4.0	1.6	0.9	0.7	0.9	3.7	7.9	46.5	2.5	5.4	45.5	0.5	0.6	84.1	2,216	821	317	126	73	53	75	171
Pascal Siakam	+593	2018-19	TOR	80	31.9	16.9	6.9	3.1	0.9	0.7	1.9	6.5	11.8	54.9	1.0	2.7	36.9	3.0	3.8	78.5	2,548	1,354	549	248	73	52	154	241
Kyle Lowry	+536	2018-19	TOR	65	34.0	14.2	4.8	8.7	1.4	0.5	2.8	4.7	11.4	41.1	2.4	7.0	34.7	2.5	3.0	83.0	2,213	926	312	564	91	31	182	166
DeMar DeRozan	+440	2017-18	TOR	80	33.9	23.0	3.9	5.2	1.1	0.3	2.2	8.1	17.7	45.6	1.1	3.6	31.0	5.8	7.0	82.5	2,712	1,840	315	417	85	22	175	151
Patrick Patterson	+403	2015-16	TOR	79	25.6	6.9	4.3	1.2	0.7	0.4	0.8	2.6	6.2	41.4	1.3	3.7	36.2	0.4	0.4	85.3	2,020	543	342	94	53	32	65	128
Pascal Siakam	+399	2019-20	TOR	60	35.2	22.9	7.3	3.5	1.0	0.9	2.5	8.3	18.4	45.3	2.2	6.1	35.9	4.0	5.1	79.2	2,110	1,371	439	207	61	53	148	170
Kyle Lowry	+399	2017-18	TOR	78	32.2	16.2	5.6	6.9	1.1	0.2	2.3	5.2	12.1	42.7	3.1	7.6	39.9	2.9	3.3	85.4	2,510	1,267	434	537	85	19	183	192
Kyle Lowry	+380	2015-16	TOR	77	37.0	21.2	4.7	6.4	2.1	0.4	2.9	6.6	15.6	42.7	2.8	7.1	38.8	5.2	6.4	81.1	2,851	1,634	365	494	158	34	225	211
Kyle Lowry	+358	2016-17	TOR	60	37.4	22.4	4.8	7.0	1.5	0.3	2.9	7.1	15.3	46.4	3.2	7.8	41.2	5.0	6.1	81.9	2,244	1,344	286	417	88	19	173	170
Chris Bosh	+358	2007-08	TOR	67	36.2	22.3	8.7	2.6	0.9	1.0	2.3	7.6	15.3	49.4	0.1	0.4	40.0	7.0	8.3	84.4	2,425	1,496	583	171	63	67	153	157
Kawhi Leonard	+356	2018-19	TOR	60	34.0	26.6	7.3	3.3	1.8	0.4	2.0	9.3	18.8	49.6	1.9	5.0	37.1	6.1	7.1	85.4	2,040	1,596	439	199	106	24	121	87
Fred VanVleet	+352	2017-18	TOR	76	20.0	8.6	2.4	3.2	0.9	0.3	1.0	3.1	7.2	42.6	1.4	3.4	41.4	1.1	1.3	83.2	1,520	656	184	243	68	19	74	130
Patrick Patterson	+348	2016-17	TOR	65	24.6	6.8	4.5	1.2	0.6	0.4	0.6	2.4	5.9	40.1	1.4	3.9	37.2	0.7	0.9	71.7	1,599	445	293	76	40	23	38	120
Vince Carter	+323	2000-01	TOR	75	39.7	27.6	5.5	3.9	1.5	1.1	2.2	10.2	22.1	46.0	2.2	5.3	40.8	5.1	6.7	76.5	2,979	2,070	416	291	114	82	167	205
Serge Ibaka	+314	2017-18	TOR	76	27.5	12.6	6.3	0.8	0.4	1.3	1.2	5.0	10.3	48.3	1.4	3.9	36.0	1.2	1.6	79.7	2,093	959	478	62	29	99	90	209
Anthony Parker	+311	2006-07	TOR	73	33.4	12.4	3.9	2.1	1.0	0.2	1.0	4.5	9.4	47.7	1.6	3.6	44.1	1.8	2.2	83.5	2,437	903	283	153	73	11	71	135
Pascal Siakam	+300	2017-18	TOR	81	20.7	7.3	4.5	2.0	0.8	0.5	0.8	3.1	6.1	50.8	0.4	1.6	22.0	0.7	1.1	62.1	1,679	589	364	159	62	42	67	166
Fred VanVleet	+298	2018-19	TOR	64	27.5	11.0	2.6	4.8	0.9	0.3	1.3	3.8	9.4	41.0	1.8	4.6	37.8	1.5	1.8	84.3	1,760	701	167	307	57	20	82	110
Lou Williams	+295	2014-15	TOR	80	25.2	15.5	1.9	2.1	1.1	0.1	1.3	4.7	11.6	40.4	1.9	5.6	34.0	4.3	4.9	86.1	2,016	1,242	151	164	88	10	101	103
OG Anunoby	+291	2017-18	TOR	74	20.0	5.9	2.5	0.7	0.7	0.2	0.6	2.2	4.7	47.1	1.0	2.7	37.1	0.5	0.8	62.9	1,481	438	184	55	52	14	45	130
Kyle Lowry	+275	2019-20	TOR	58	36.2	19.4	5.0	7.5	1.4	0.4	3.1	5.8	13.8	41.6	2.8	8.0	35.2	5.1	5.9	85.7	2,098	1,126	292	433	82	26	178	190
Cory Joseph	+274	2015-16	TOR	80	25.6	8.5	2.6	3.1	0.8	0.3	1.3	3.2	7.3	43.9	0.4	1.4	27.3	1.7	2.2	76.4	2,046	677	210	250	63	20	102	131
OG Anunoby	+273	2019-20	TOR	69	29.9	10.6	5.3	1.6	1.4	0.7	1.1	4.1	8.2	50.5	1.3	3.3	39.0	1.0	1.5	70.6	2,066	733	364	108	96	45	79	167
Kyle Lowry	+271	2013-14	TOR	79	36.2	17.9	4.7	7.4	1.5	0.2	2.5	5.8	13.7	42.3	2.4	6.3	38.0	4.0	4.9	81.3	2,862	1,417	369	586	121	15	194	267
Jamario Moon	+271	2007-08	TOR	78	27.8	8.5	6.2	1.2	1.0	1.4	0.7	3.6	7.4	48.5	0.5	1.6	32.8	0.8	1.1	74.1	2,166	661	484	90	80	108	51	152